diff --git a/doc/api/crypto.md b/doc/api/crypto.md
index 90c3eee2419d3f..32982621613d8d 100644
--- a/doc/api/crypto.md
+++ b/doc/api/crypto.md
@@ -2578,11 +2578,27 @@ The SHA-512 fingerprint of this certificate.
 
 <!-- YAML
 added: v15.6.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs-private/node-private/pull/300
+    description: Parts of this string may be encoded as JSON string literals
+                 in response to CVE-2021-44532.
 -->
 
 * Type: {string}
 
-The information access content of this certificate.
+A textual representation of the certificate's authority information access
+extension.
+
+This is a line feed separated list of access descriptions. Each line begins with
+the access method and the kind of the access location, followed by a colon and
+the value associated with the access location.
+
+After the prefix denoting the access method and the kind of the access location,
+the remainder of each line might be enclosed in quotes to indicate that the
+value is a JSON string literal. For backward compatibility, Node.js only uses
+JSON string literals within this property when necessary to avoid ambiguity.
+Third-party code should be prepared to handle both possible entry formats.
 
 ### `x509.issuer`
 
@@ -2659,12 +2675,32 @@ The complete subject of this certificate.
 
 <!-- YAML
 added: v15.6.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs-private/node-private/pull/300
+    description: Parts of this string may be encoded as JSON string literals
+                 in response to CVE-2021-44532.
 -->
 
 * Type: {string}
 
 The subject alternative name specified for this certificate.
 
+This is a comma-separated list of subject alternative names. Each entry begins
+with a string identifying the kind of the subject alternative name followed by
+a colon and the value associated with the entry.
+
+Earlier versions of Node.js incorrectly assumed that it is safe to split this
+property at the two-character sequence `', '` (see [CVE-2021-44532][]). However,
+both malicious and legitimate certificates can contain subject alternative names
+that include this sequence when represented as a string.
+
+After the prefix denoting the type of the entry, the remainder of each entry
+might be enclosed in quotes to indicate that the value is a JSON string literal.
+For backward compatibility, Node.js only uses JSON string literals within this
+property when necessary to avoid ambiguity. Third-party code should be prepared
+to handle both possible entry formats.
+
 ### `x509.toJSON()`
 
 <!-- YAML
@@ -5878,6 +5914,7 @@ See the [list of SSL OP Flags][] for details.
 
 [AEAD algorithms]: https://en.wikipedia.org/wiki/Authenticated_encryption
 [CCM mode]: #ccm-mode
+[CVE-2021-44532]: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-44532
 [Caveats]: #support-for-weak-or-compromised-algorithms
 [Crypto constants]: #crypto-constants
 [HTML 5.2]: https://www.w3.org/TR/html52/changes.html#features-removed
diff --git a/doc/api/errors.md b/doc/api/errors.md
index cfe43c4ae5d5e1..a22f125ce62c98 100644
--- a/doc/api/errors.md
+++ b/doc/api/errors.md
@@ -2550,6 +2550,15 @@ An unspecified or non-specific system error has occurred within the Node.js
 process. The error object will have an `err.info` object property with
 additional details.
 
+<a id="ERR_TLS_CERT_ALTNAME_FORMAT"></a>
+
+### `ERR_TLS_CERT_ALTNAME_FORMAT`
+
+This error is thrown by `checkServerIdentity` if a user-supplied
+`subjectaltname` property violates encoding rules. Certificate objects produced
+by Node.js itself always comply with encoding rules and will never cause
+this error.
+
 <a id="ERR_TLS_CERT_ALTNAME_INVALID"></a>
 
 ### `ERR_TLS_CERT_ALTNAME_INVALID`
diff --git a/lib/_tls_common.js b/lib/_tls_common.js
index 21b22a42507c5b..cb3f08bf28793e 100644
--- a/lib/_tls_common.js
+++ b/lib/_tls_common.js
@@ -25,6 +25,7 @@ const tls = require('tls');
 
 const {
   ArrayPrototypePush,
+  JSONParse,
   ObjectCreate,
   StringPrototypeReplace,
 } = primordials;
@@ -137,6 +138,14 @@ function translatePeerCertificate(c) {
     // XXX: More key validation?
     StringPrototypeReplace(info, /([^\n:]*):([^\n]*)(?:\n|$)/g,
                            (all, key, val) => {
+                             if (val.charCodeAt(0) === 0x22) {
+                               // The translatePeerCertificate function is only
+                               // used on internally created legacy certificate
+                               // objects, and any value that contains a quote
+                               // will always be a valid JSON string literal,
+                               // so this should never throw.
+                               val = JSONParse(val);
+                             }
                              if (key in c.infoAccess)
                                ArrayPrototypePush(c.infoAccess[key], val);
                              else
diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index 309f6bb3105341..c5b8146b851bf0 100644
--- a/lib/internal/errors.js
+++ b/lib/internal/errors.js
@@ -1525,6 +1525,8 @@ E('ERR_STREAM_WRAP', 'Stream has StringDecoder set or is in objectMode', Error);
 E('ERR_STREAM_WRITE_AFTER_END', 'write after end', Error);
 E('ERR_SYNTHETIC', 'JavaScript Callstack', Error);
 E('ERR_SYSTEM_ERROR', 'A system error occurred', SystemError);
+E('ERR_TLS_CERT_ALTNAME_FORMAT', 'Invalid subject alternative name string',
+  SyntaxError);
 E('ERR_TLS_CERT_ALTNAME_INVALID', function(reason, host, cert) {
   this.reason = reason;
   this.host = host;
diff --git a/lib/tls.js b/lib/tls.js
index 683736460b1ef7..eaba340d572090 100644
--- a/lib/tls.js
+++ b/lib/tls.js
@@ -30,20 +30,25 @@ const {
   ArrayPrototypePush,
   ArrayPrototypeReduce,
   ArrayPrototypeSome,
+  JSONParse,
   ObjectDefineProperty,
   ObjectFreeze,
+  RegExpPrototypeExec,
   RegExpPrototypeTest,
   StringFromCharCode,
   StringPrototypeCharCodeAt,
   StringPrototypeEndsWith,
   StringPrototypeIncludes,
+  StringPrototypeIndexOf,
   StringPrototypeReplace,
   StringPrototypeSlice,
   StringPrototypeSplit,
   StringPrototypeStartsWith,
+  StringPrototypeSubstring,
 } = primordials;
 
 const {
+  ERR_TLS_CERT_ALTNAME_FORMAT,
   ERR_TLS_CERT_ALTNAME_INVALID,
   ERR_OUT_OF_RANGE
 } = require('internal/errors').codes;
@@ -227,6 +232,45 @@ function check(hostParts, pattern, wildcards) {
   return true;
 }
 
+// This pattern is used to determine the length of escaped sequences within
+// the subject alt names string. It allows any valid JSON string literal.
+// This MUST match the JSON specification (ECMA-404 / RFC8259) exactly.
+const jsonStringPattern =
+  // eslint-disable-next-line no-control-regex
+  /^"(?:[^"\\\u0000-\u001f]|\\(?:["\\/bfnrt]|u[0-9a-fA-F]{4}))*"/;
+
+function splitEscapedAltNames(altNames) {
+  const result = [];
+  let currentToken = '';
+  let offset = 0;
+  while (offset !== altNames.length) {
+    const nextSep = StringPrototypeIndexOf(altNames, ', ', offset);
+    const nextQuote = StringPrototypeIndexOf(altNames, '"', offset);
+    if (nextQuote !== -1 && (nextSep === -1 || nextQuote < nextSep)) {
+      // There is a quote character and there is no separator before the quote.
+      currentToken += StringPrototypeSubstring(altNames, offset, nextQuote);
+      const match = RegExpPrototypeExec(
+        jsonStringPattern, StringPrototypeSubstring(altNames, nextQuote));
+      if (!match) {
+        throw new ERR_TLS_CERT_ALTNAME_FORMAT();
+      }
+      currentToken += JSONParse(match[0]);
+      offset = nextQuote + match[0].length;
+    } else if (nextSep !== -1) {
+      // There is a separator and no quote before it.
+      currentToken += StringPrototypeSubstring(altNames, offset, nextSep);
+      ArrayPrototypePush(result, currentToken);
+      currentToken = '';
+      offset = nextSep + 2;
+    } else {
+      currentToken += StringPrototypeSubstring(altNames, offset);
+      offset = altNames.length;
+    }
+  }
+  ArrayPrototypePush(result, currentToken);
+  return result;
+}
+
 exports.checkServerIdentity = function checkServerIdentity(hostname, cert) {
   const subject = cert.subject;
   const altNames = cert.subjectaltname;
@@ -237,7 +281,9 @@ exports.checkServerIdentity = function checkServerIdentity(hostname, cert) {
   hostname = '' + hostname;
 
   if (altNames) {
-    const splitAltNames = StringPrototypeSplit(altNames, ', ');
+    const splitAltNames = StringPrototypeIncludes(altNames, '"') ?
+      splitEscapedAltNames(altNames) :
+      StringPrototypeSplit(altNames, ', ');
     ArrayPrototypeForEach(splitAltNames, (name) => {
       if (StringPrototypeStartsWith(name, 'DNS:')) {
         ArrayPrototypePush(dnsNames, StringPrototypeSlice(name, 4));
diff --git a/src/crypto/crypto_common.cc b/src/crypto/crypto_common.cc
index e663e84c07a778..02ed01ad7563cd 100644
--- a/src/crypto/crypto_common.cc
+++ b/src/crypto/crypto_common.cc
@@ -619,39 +619,320 @@ MaybeLocal<Value> GetValidFrom(
   return ToV8Value(env, bio);
 }
 
-bool SafeX509ExtPrint(const BIOPointer& out, X509_EXTENSION* ext) {
-  const X509V3_EXT_METHOD* method = X509V3_EXT_get(ext);
+static inline bool IsSafeAltName(const char* name, size_t length, bool utf8) {
+  for (size_t i = 0; i < length; i++) {
+    char c = name[i];
+    switch (c) {
+    case '"':
+    case '\\':
+      // These mess with encoding rules.
+      // Fall through.
+    case ',':
+      // Commas make it impossible to split the list of subject alternative
+      // names unambiguously, which is why we have to escape.
+      // Fall through.
+    case '\'':
+      // Single quotes are unlikely to appear in any legitimate values, but they
+      // could be used to make a value look like it was escaped (i.e., enclosed
+      // in single/double quotes).
+      return false;
+    default:
+      if (utf8) {
+        // In UTF8 strings, we require escaping for any ASCII control character,
+        // but NOT for non-ASCII characters. Note that all bytes of any code
+        // point that consists of more than a single byte have their MSB set.
+        if (static_cast<unsigned char>(c) < ' ' || c == '\x7f') {
+          return false;
+        }
+      } else {
+        // Check if the char is a control character or non-ASCII character. Note
+        // that char may or may not be a signed type. Regardless, non-ASCII
+        // values will always be outside of this range.
+        if (c < ' ' || c > '~') {
+          return false;
+        }
+      }
+    }
+  }
+  return true;
+}
 
-  if (method != X509V3_EXT_get_nid(NID_subject_alt_name))
-    return false;
+static inline void PrintAltName(const BIOPointer& out, const char* name,
+                                size_t length, bool utf8,
+                                const char* safe_prefix) {
+  if (IsSafeAltName(name, length, utf8)) {
+    // For backward-compatibility, append "safe" names without any
+    // modifications.
+    if (safe_prefix != nullptr) {
+      BIO_printf(out.get(), "%s:", safe_prefix);
+    }
+    BIO_write(out.get(), name, length);
+  } else {
+    // If a name is not "safe", we cannot embed it without special
+    // encoding. This does not usually happen, but we don't want to hide
+    // it from the user either. We use JSON compatible escaping here.
+    BIO_write(out.get(), "\"", 1);
+    if (safe_prefix != nullptr) {
+      BIO_printf(out.get(), "%s:", safe_prefix);
+    }
+    for (size_t j = 0; j < length; j++) {
+      char c = static_cast<char>(name[j]);
+      if (c == '\\') {
+        BIO_write(out.get(), "\\\\", 2);
+      } else if (c == '"') {
+        BIO_write(out.get(), "\\\"", 2);
+      } else if ((c >= ' ' && c != ',' && c <= '~') || (utf8 && (c & 0x80))) {
+        // Note that the above condition explicitly excludes commas, which means
+        // that those are encoded as Unicode escape sequences in the "else"
+        // block. That is not strictly necessary, and Node.js itself would parse
+        // it correctly either way. We only do this to account for third-party
+        // code that might be splitting the string at commas (as Node.js itself
+        // used to do).
+        BIO_write(out.get(), &c, 1);
+      } else {
+        // Control character or non-ASCII character. We treat everything as
+        // Latin-1, which corresponds to the first 255 Unicode code points.
+        const char hex[] = "0123456789abcdef";
+        char u[] = { '\\', 'u', '0', '0', hex[(c & 0xf0) >> 4], hex[c & 0x0f] };
+        BIO_write(out.get(), u, sizeof(u));
+      }
+    }
+    BIO_write(out.get(), "\"", 1);
+  }
+}
+
+static inline void PrintLatin1AltName(const BIOPointer& out,
+                                      const ASN1_IA5STRING* name,
+                                      const char* safe_prefix = nullptr) {
+  PrintAltName(out, reinterpret_cast<const char*>(name->data), name->length,
+               false, safe_prefix);
+}
+
+static inline void PrintUtf8AltName(const BIOPointer& out,
+                                    const ASN1_UTF8STRING* name,
+                                    const char* safe_prefix = nullptr) {
+  PrintAltName(out, reinterpret_cast<const char*>(name->data), name->length,
+               true, safe_prefix);
+}
+
+// This function currently emulates the behavior of i2v_GENERAL_NAME in a safer
+// and less ambiguous way.
+// TODO(tniessen): gradually improve the format in the next major version(s)
+static bool PrintGeneralName(const BIOPointer& out, const GENERAL_NAME* gen) {
+  if (gen->type == GEN_DNS) {
+    ASN1_IA5STRING* name = gen->d.dNSName;
+    BIO_write(out.get(), "DNS:", 4);
+    // Note that the preferred name syntax (see RFCs 5280 and 1034) with
+    // wildcards is a subset of what we consider "safe", so spec-compliant DNS
+    // names will never need to be escaped.
+    PrintLatin1AltName(out, name);
+  } else if (gen->type == GEN_EMAIL) {
+    ASN1_IA5STRING* name = gen->d.rfc822Name;
+    BIO_write(out.get(), "email:", 6);
+    PrintLatin1AltName(out, name);
+  } else if (gen->type == GEN_URI) {
+    ASN1_IA5STRING* name = gen->d.uniformResourceIdentifier;
+    BIO_write(out.get(), "URI:", 4);
+    // The set of "safe" names was designed to include just about any URI,
+    // with a few exceptions, most notably URIs that contains commas (see
+    // RFC 2396). In other words, most legitimate URIs will not require
+    // escaping.
+    PrintLatin1AltName(out, name);
+  } else if (gen->type == GEN_DIRNAME) {
+    // For backward compatibility, use X509_NAME_oneline to print the
+    // X509_NAME object. The format is non standard and should be avoided
+    // elsewhere, but conveniently, the function produces ASCII and the output
+    // is unlikely to contains commas or other characters that would require
+    // escaping. With that in mind, note that it SHOULD NOT produce ASCII
+    // output since an RFC5280 AttributeValue may be a UTF8String.
+    // TODO(tniessen): switch to RFC2253 rules in a major release
+    BIO_printf(out.get(), "DirName:");
+    char oline[256];
+    if (X509_NAME_oneline(gen->d.dirn, oline, sizeof(oline)) != nullptr) {
+      PrintAltName(out, oline, strlen(oline), false, nullptr);
+    } else {
+      return false;
+    }
+  } else if (gen->type == GEN_IPADD) {
+    BIO_printf(out.get(), "IP Address:");
+    const ASN1_OCTET_STRING* ip = gen->d.ip;
+    const unsigned char* b = ip->data;
+    if (ip->length == 4) {
+      BIO_printf(out.get(), "%d.%d.%d.%d", b[0], b[1], b[2], b[3]);
+    } else if (ip->length == 16) {
+      for (unsigned int j = 0; j < 8; j++) {
+        uint16_t pair = (b[2 * j] << 8) | b[2 * j + 1];
+        BIO_printf(out.get(), (j == 0) ? "%X" : ":%X", pair);
+      }
+    } else {
+#if OPENSSL_VERSION_MAJOR >= 3
+      BIO_printf(out.get(), "<invalid length=%d>", ip->length);
+#else
+      BIO_printf(out.get(), "<invalid>");
+#endif
+    }
+  } else if (gen->type == GEN_RID) {
+    // TODO(tniessen): unlike OpenSSL's default implementation, never print the
+    // OID as text and instead always print its numeric representation, which is
+    // backward compatible in practice and more future proof (see OBJ_obj2txt).
+    char oline[256];
+    i2t_ASN1_OBJECT(oline, sizeof(oline), gen->d.rid);
+    BIO_printf(out.get(), "Registered ID:%s", oline);
+  } else if (gen->type == GEN_OTHERNAME) {
+    // TODO(tniessen): the format that is used here is based on OpenSSL's
+    // implementation of i2v_GENERAL_NAME (as of OpenSSL 3.0.1), mostly for
+    // backward compatibility. It is somewhat awkward, especially when passed to
+    // translatePeerCertificate, and should be changed in the future, probably
+    // to the format used by GENERAL_NAME_print (in a major release).
+    bool unicode = true;
+    const char* prefix = nullptr;
+    // OpenSSL 1.1.1 does not support othername in i2v_GENERAL_NAME and may not
+    // define these NIDs.
+#if OPENSSL_VERSION_MAJOR >= 3
+    int nid = OBJ_obj2nid(gen->d.otherName->type_id);
+    switch (nid) {
+      case NID_id_on_SmtpUTF8Mailbox:
+        prefix = " SmtpUTF8Mailbox:";
+        break;
+      case NID_XmppAddr:
+        prefix = " XmppAddr:";
+        break;
+      case NID_SRVName:
+        prefix = " SRVName:";
+        unicode = false;
+        break;
+      case NID_ms_upn:
+        prefix = " UPN:";
+        break;
+      case NID_NAIRealm:
+        prefix = " NAIRealm:";
+        break;
+    }
+#endif  // OPENSSL_VERSION_MAJOR >= 3
+    int val_type = gen->d.otherName->value->type;
+    if (prefix == nullptr ||
+        (unicode && val_type != V_ASN1_UTF8STRING) ||
+        (!unicode && val_type != V_ASN1_IA5STRING)) {
+      BIO_printf(out.get(), "othername:<unsupported>");
+    } else {
+      BIO_printf(out.get(), "othername:");
+      if (unicode) {
+        PrintUtf8AltName(out, gen->d.otherName->value->value.utf8string,
+                         prefix);
+      } else {
+        PrintLatin1AltName(out, gen->d.otherName->value->value.ia5string,
+                           prefix);
+      }
+    }
+  } else if (gen->type == GEN_X400) {
+    // TODO(tniessen): this is what OpenSSL does, implement properly instead
+    BIO_printf(out.get(), "X400Name:<unsupported>");
+  } else if (gen->type == GEN_EDIPARTY) {
+    // TODO(tniessen): this is what OpenSSL does, implement properly instead
+    BIO_printf(out.get(), "EdiPartyName:<unsupported>");
+  } else {
+    // This is safe because X509V3_EXT_d2i would have returned nullptr in this
+    // case already.
+    UNREACHABLE();
+  }
+
+  return true;
+}
+
+bool SafeX509SubjectAltNamePrint(const BIOPointer& out, X509_EXTENSION* ext) {
+  const X509V3_EXT_METHOD* method = X509V3_EXT_get(ext);
+  CHECK(method == X509V3_EXT_get_nid(NID_subject_alt_name));
 
   GENERAL_NAMES* names = static_cast<GENERAL_NAMES*>(X509V3_EXT_d2i(ext));
   if (names == nullptr)
     return false;
 
+  bool ok = true;
+
   for (int i = 0; i < sk_GENERAL_NAME_num(names); i++) {
     GENERAL_NAME* gen = sk_GENERAL_NAME_value(names, i);
 
     if (i != 0)
       BIO_write(out.get(), ", ", 2);
 
-    if (gen->type == GEN_DNS) {
-      ASN1_IA5STRING* name = gen->d.dNSName;
-
-      BIO_write(out.get(), "DNS:", 4);
-      BIO_write(out.get(), name->data, name->length);
-    } else {
-      STACK_OF(CONF_VALUE)* nval = i2v_GENERAL_NAME(
-          const_cast<X509V3_EXT_METHOD*>(method), gen, nullptr);
-      if (nval == nullptr)
-        return false;
-      X509V3_EXT_val_prn(out.get(), nval, 0, 0);
-      sk_CONF_VALUE_pop_free(nval, X509V3_conf_free);
+    if (!(ok = PrintGeneralName(out, gen))) {
+      break;
     }
   }
   sk_GENERAL_NAME_pop_free(names, GENERAL_NAME_free);
 
-  return true;
+  return ok;
+}
+
+bool SafeX509InfoAccessPrint(const BIOPointer& out, X509_EXTENSION* ext) {
+  const X509V3_EXT_METHOD* method = X509V3_EXT_get(ext);
+  CHECK(method == X509V3_EXT_get_nid(NID_info_access));
+
+  AUTHORITY_INFO_ACCESS* descs =
+      static_cast<AUTHORITY_INFO_ACCESS*>(X509V3_EXT_d2i(ext));
+  if (descs == nullptr)
+    return false;
+
+  bool ok = true;
+
+  for (int i = 0; i < sk_ACCESS_DESCRIPTION_num(descs); i++) {
+    ACCESS_DESCRIPTION* desc = sk_ACCESS_DESCRIPTION_value(descs, i);
+
+    if (i != 0)
+      BIO_write(out.get(), "\n", 1);
+
+    char objtmp[80];
+    i2t_ASN1_OBJECT(objtmp, sizeof(objtmp), desc->method);
+    BIO_printf(out.get(), "%s - ", objtmp);
+    if (!(ok = PrintGeneralName(out, desc->location))) {
+      break;
+    }
+  }
+  sk_ACCESS_DESCRIPTION_pop_free(descs, ACCESS_DESCRIPTION_free);
+
+#if OPENSSL_VERSION_MAJOR < 3
+  BIO_write(out.get(), "\n", 1);
+#endif
+
+  return ok;
+}
+
+v8::MaybeLocal<v8::Value> GetSubjectAltNameString(
+    Environment* env,
+    const BIOPointer& bio,
+    X509* cert) {
+  int index = X509_get_ext_by_NID(cert, NID_subject_alt_name, -1);
+  if (index < 0)
+    return Undefined(env->isolate());
+
+  X509_EXTENSION* ext = X509_get_ext(cert, index);
+  CHECK_NOT_NULL(ext);
+
+  if (!SafeX509SubjectAltNamePrint(bio, ext)) {
+    USE(BIO_reset(bio.get()));
+    return v8::Null(env->isolate());
+  }
+
+  return ToV8Value(env, bio);
+}
+
+v8::MaybeLocal<v8::Value> GetInfoAccessString(
+    Environment* env,
+    const BIOPointer& bio,
+    X509* cert) {
+  int index = X509_get_ext_by_NID(cert, NID_info_access, -1);
+  if (index < 0)
+    return Undefined(env->isolate());
+
+  X509_EXTENSION* ext = X509_get_ext(cert, index);
+  CHECK_NOT_NULL(ext);
+
+  if (!SafeX509InfoAccessPrint(bio, ext)) {
+    USE(BIO_reset(bio.get()));
+    return v8::Null(env->isolate());
+  }
+
+  return ToV8Value(env, bio);
 }
 
 MaybeLocal<Value> GetIssuerString(
@@ -931,11 +1212,11 @@ MaybeLocal<Object> X509ToObject(Environment* env, X509* cert) {
       !Set<Value>(context,
                   info,
                   env->subjectaltname_string(),
-                  GetInfoString<NID_subject_alt_name>(env, bio, cert)) ||
+                  GetSubjectAltNameString(env, bio, cert)) ||
       !Set<Value>(context,
                   info,
                   env->infoaccess_string(),
-                  GetInfoString<NID_info_access>(env, bio, cert))) {
+                  GetInfoAccessString(env, bio, cert))) {
     return MaybeLocal<Object>();
   }
 
diff --git a/src/crypto/crypto_common.h b/src/crypto/crypto_common.h
index 2c578b7be435cb..b916c4c7eb6126 100644
--- a/src/crypto/crypto_common.h
+++ b/src/crypto/crypto_common.h
@@ -140,7 +140,7 @@ v8::MaybeLocal<v8::Value> GetSerialNumber(Environment* env, X509* cert);
 v8::MaybeLocal<v8::Object> GetRawDERCertificate(Environment* env, X509* cert);
 
 v8::Local<v8::Value> ToV8Value(Environment* env, const BIOPointer& bio);
-bool SafeX509ExtPrint(const BIOPointer& out, X509_EXTENSION* ext);
+bool SafeX509SubjectAltNamePrint(const BIOPointer& out, X509_EXTENSION* ext);
 
 v8::MaybeLocal<v8::Value> GetSubject(
     Environment* env,
@@ -152,26 +152,15 @@ v8::MaybeLocal<v8::Value> GetIssuerString(
     const BIOPointer& bio,
     X509* cert);
 
-template <int nid>
-v8::MaybeLocal<v8::Value> GetInfoString(
+v8::MaybeLocal<v8::Value> GetSubjectAltNameString(
     Environment* env,
     const BIOPointer& bio,
-    X509* cert) {
-  int index = X509_get_ext_by_NID(cert, nid, -1);
-  if (index < 0)
-    return Undefined(env->isolate());
-
-  X509_EXTENSION* ext = X509_get_ext(cert, index);
-  CHECK_NOT_NULL(ext);
-
-  if (!SafeX509ExtPrint(bio, ext) &&
-      X509V3_EXT_print(bio.get(), ext, 0, 0) != 1) {
-    USE(BIO_reset(bio.get()));
-    return v8::Null(env->isolate());
-  }
+    X509* cert);
 
-  return ToV8Value(env, bio);
-}
+v8::MaybeLocal<v8::Value> GetInfoAccessString(
+    Environment* env,
+    const BIOPointer& bio,
+    X509* cert);
 
 }  // namespace crypto
 }  // namespace node
diff --git a/src/crypto/crypto_x509.cc b/src/crypto/crypto_x509.cc
index f2fa18b5b6b12e..8ad453680bf998 100644
--- a/src/crypto/crypto_x509.cc
+++ b/src/crypto/crypto_x509.cc
@@ -217,7 +217,7 @@ void X509Certificate::SubjectAltName(const FunctionCallbackInfo<Value>& args) {
   ASSIGN_OR_RETURN_UNWRAP(&cert, args.Holder());
   BIOPointer bio(BIO_new(BIO_s_mem()));
   Local<Value> ret;
-  if (GetInfoString<NID_subject_alt_name>(env, bio, cert->get()).ToLocal(&ret))
+  if (GetSubjectAltNameString(env, bio, cert->get()).ToLocal(&ret))
     args.GetReturnValue().Set(ret);
 }
 
@@ -227,7 +227,7 @@ void X509Certificate::InfoAccess(const FunctionCallbackInfo<Value>& args) {
   ASSIGN_OR_RETURN_UNWRAP(&cert, args.Holder());
   BIOPointer bio(BIO_new(BIO_s_mem()));
   Local<Value> ret;
-  if (GetInfoString<NID_info_access>(env, bio, cert->get()).ToLocal(&ret))
+  if (GetInfoAccessString(env, bio, cert->get()).ToLocal(&ret))
     args.GetReturnValue().Set(ret);
 }
 
diff --git a/test/fixtures/keys/Makefile b/test/fixtures/keys/Makefile
index a825cace1bf7bb..e5dab9e046dd17 100644
--- a/test/fixtures/keys/Makefile
+++ b/test/fixtures/keys/Makefile
@@ -85,6 +85,8 @@ all: \
   ec_p521_public.pem \
   ec_secp256k1_private.pem \
   ec_secp256k1_public.pem \
+  incorrect_san_correct_subject-cert.pem \
+  incorrect_san_correct_subject-key.pem \
 
 #
 # Create Certificate Authority: ca1
@@ -781,6 +783,18 @@ ec_secp256k1_private.pem:
 ec_secp256k1_public.pem: ec_secp256k1_private.pem
 	openssl ec -in ec_secp256k1_private.pem -pubout -out ec_secp256k1_public.pem
 
+incorrect_san_correct_subject-cert.pem: incorrect_san_correct_subject-key.pem
+	openssl req -x509 \
+	            -key incorrect_san_correct_subject-key.pem \
+	            -out incorrect_san_correct_subject-cert.pem \
+	            -sha256 \
+	            -days 3650 \
+	            -subj "/CN=good.example.com" \
+	            -addext "subjectAltName = DNS:evil.example.com"
+
+incorrect_san_correct_subject-key.pem:
+	openssl ecparam -name prime256v1 -genkey -noout -out incorrect_san_correct_subject-key.pem
+
 clean:
 	rm -f *.pfx *.pem *.srl ca2-database.txt ca2-serial fake-startcom-root-serial *.print *.old fake-startcom-root-issued-certs/*.pem
 	@> fake-startcom-root-database.txt
diff --git a/test/fixtures/keys/incorrect_san_correct_subject-cert.pem b/test/fixtures/keys/incorrect_san_correct_subject-cert.pem
new file mode 100644
index 00000000000000..787d9f113511d6
--- /dev/null
+++ b/test/fixtures/keys/incorrect_san_correct_subject-cert.pem
@@ -0,0 +1,11 @@
+-----BEGIN CERTIFICATE-----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=
+-----END CERTIFICATE-----
diff --git a/test/fixtures/keys/incorrect_san_correct_subject-key.pem b/test/fixtures/keys/incorrect_san_correct_subject-key.pem
new file mode 100644
index 00000000000000..f7f51253a8f7ed
--- /dev/null
+++ b/test/fixtures/keys/incorrect_san_correct_subject-key.pem
@@ -0,0 +1,5 @@
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEIOOVRgLS3H2T2fUhj4ASCFq60ySwO6yvSK6rvZHldAHuoAoGCCqGSM49
+AwEHoUQDQgAEkPwimubjGbi2LLJzTpuwz3cNyOQ6GtEKcn93Eu2hmrXyt7bmPKhu
+5yeThrZdVji/4DdL0UTdPygP4kSco2n88w==
+-----END EC PRIVATE KEY-----
diff --git a/test/fixtures/x509-escaping/.gitignore b/test/fixtures/x509-escaping/.gitignore
new file mode 100644
index 00000000000000..504afef81fbadc
--- /dev/null
+++ b/test/fixtures/x509-escaping/.gitignore
@@ -0,0 +1,2 @@
+node_modules/
+package-lock.json
diff --git a/test/fixtures/x509-escaping/alt-0-cert.pem b/test/fixtures/x509-escaping/alt-0-cert.pem
new file mode 100644
index 00000000000000..30e6fa6c3fa83a
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-0-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
+MIIE5jCCAs6gAwIBAgIBATANBgkqhkiG9w0BAQsFADAbMRkwFwYDVQQDExBldmls
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+O6Zqbod3EImVnQ==
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-1-cert.pem b/test/fixtures/x509-escaping/alt-1-cert.pem
new file mode 100644
index 00000000000000..63883c2bbf7f91
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-1-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
+MIIE0zCCArugAwIBAgIBATANBgkqhkiG9w0BAQsFADAbMRkwFwYDVQQDExBldmls
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+aMHO+PIgudWwGPhkABtrc/1jC+Yfy+GCtih10zBagoN9/DSugh0H
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-10-cert.pem b/test/fixtures/x509-escaping/alt-10-cert.pem
new file mode 100644
index 00000000000000..14bec45d284e26
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-10-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
+MIIExTCCAq2gAwIBAgIBATANBgkqhkiG9w0BAQsFADAbMRkwFwYDVQQDExBldmls
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+VGhc/foVd+vBuM3jXEdGR+DN/dEu+HZrhQ==
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-11-cert.pem b/test/fixtures/x509-escaping/alt-11-cert.pem
new file mode 100644
index 00000000000000..694cb7e9d8d879
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-11-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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+NRDSdNS1/rJEH1gLQEh4SGMs9iY5Vv+kx28=
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-12-cert.pem b/test/fixtures/x509-escaping/alt-12-cert.pem
new file mode 100644
index 00000000000000..7e48ebdf052c94
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-12-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
+MIIE0DCCArigAwIBAgIBATANBgkqhkiG9w0BAQsFADAbMRkwFwYDVQQDExBldmls
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diff --git a/test/fixtures/x509-escaping/alt-13-cert.pem b/test/fixtures/x509-escaping/alt-13-cert.pem
new file mode 100644
index 00000000000000..574ad1ca8f3cf9
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-13-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-14-cert.pem b/test/fixtures/x509-escaping/alt-14-cert.pem
new file mode 100644
index 00000000000000..0265b5992c1dbc
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-14-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-15-cert.pem b/test/fixtures/x509-escaping/alt-15-cert.pem
new file mode 100644
index 00000000000000..70a98fb90bb96f
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-15-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-16-cert.pem b/test/fixtures/x509-escaping/alt-16-cert.pem
new file mode 100644
index 00000000000000..64f852ceebb476
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-16-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-17-cert.pem b/test/fixtures/x509-escaping/alt-17-cert.pem
new file mode 100644
index 00000000000000..f09f41b91841d5
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-17-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-18-cert.pem b/test/fixtures/x509-escaping/alt-18-cert.pem
new file mode 100644
index 00000000000000..341ac0b7cec24d
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-18-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-19-cert.pem b/test/fixtures/x509-escaping/alt-19-cert.pem
new file mode 100644
index 00000000000000..f16318420442e2
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-19-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-2-cert.pem b/test/fixtures/x509-escaping/alt-2-cert.pem
new file mode 100644
index 00000000000000..6ae58f56360276
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-2-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-20-cert.pem b/test/fixtures/x509-escaping/alt-20-cert.pem
new file mode 100644
index 00000000000000..eca176f2df0c28
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-20-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-21-cert.pem b/test/fixtures/x509-escaping/alt-21-cert.pem
new file mode 100644
index 00000000000000..16d5e7265bc3f5
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-21-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-22-cert.pem b/test/fixtures/x509-escaping/alt-22-cert.pem
new file mode 100644
index 00000000000000..5f89b00dfdce1f
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-22-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-23-cert.pem b/test/fixtures/x509-escaping/alt-23-cert.pem
new file mode 100644
index 00000000000000..5cd6795cded659
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-23-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-24-cert.pem b/test/fixtures/x509-escaping/alt-24-cert.pem
new file mode 100644
index 00000000000000..2a858dd39a2db9
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-24-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-25-cert.pem b/test/fixtures/x509-escaping/alt-25-cert.pem
new file mode 100644
index 00000000000000..695b8ebba88ceb
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-25-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-26-cert.pem b/test/fixtures/x509-escaping/alt-26-cert.pem
new file mode 100644
index 00000000000000..1204d95a8a5793
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-26-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-27-cert.pem b/test/fixtures/x509-escaping/alt-27-cert.pem
new file mode 100644
index 00000000000000..268abdd300914f
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-27-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-28-cert.pem b/test/fixtures/x509-escaping/alt-28-cert.pem
new file mode 100644
index 00000000000000..147fba3aff2fae
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-28-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-29-cert.pem b/test/fixtures/x509-escaping/alt-29-cert.pem
new file mode 100644
index 00000000000000..434bda3e8e7988
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-29-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-3-cert.pem b/test/fixtures/x509-escaping/alt-3-cert.pem
new file mode 100644
index 00000000000000..59185b64a4dc5d
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-3-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-30-cert.pem b/test/fixtures/x509-escaping/alt-30-cert.pem
new file mode 100644
index 00000000000000..1b67d1f7823ad1
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-30-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-4-cert.pem b/test/fixtures/x509-escaping/alt-4-cert.pem
new file mode 100644
index 00000000000000..086af8e02e2c19
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-4-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
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diff --git a/test/fixtures/x509-escaping/alt-5-cert.pem b/test/fixtures/x509-escaping/alt-5-cert.pem
new file mode 100644
index 00000000000000..04a918008c67b8
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-5-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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+05oWMsCMDyzxvFDv92w=
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-6-cert.pem b/test/fixtures/x509-escaping/alt-6-cert.pem
new file mode 100644
index 00000000000000..664351995793fb
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-6-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
+MIIEyzCCArOgAwIBAgIBATANBgkqhkiG9w0BAQsFADAbMRkwFwYDVQQDExBldmls
+LmV4YW1wbGUuY29tMB4XDTIxMTIyMDE0NTczNVoXDTMxMTIxODE0NTczNVowGzEZ
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+X+now5ObP73ufyFwYGsSgblivHUX4z/zAt4kp4AMXw==
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-7-cert.pem b/test/fixtures/x509-escaping/alt-7-cert.pem
new file mode 100644
index 00000000000000..6c0f287a1be1f7
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-7-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
+MIIE0jCCArqgAwIBAgIBATANBgkqhkiG9w0BAQsFADAbMRkwFwYDVQQDExBldmls
+LmV4YW1wbGUuY29tMB4XDTIxMTIyMDE0NTczNVoXDTMxMTIxODE0NTczNVowGzEZ
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+jSUtNHUCJaC3E9yTaIDc8jMli9s5/ElDZRkPxRP8o4VOt9KcLvU=
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-8-cert.pem b/test/fixtures/x509-escaping/alt-8-cert.pem
new file mode 100644
index 00000000000000..201b520f8bf976
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-8-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
+MIIExDCCAqygAwIBAgIBATANBgkqhkiG9w0BAQsFADAbMRkwFwYDVQQDExBldmls
+LmV4YW1wbGUuY29tMB4XDTIxMTIyMDE0NTczNVoXDTMxMTIxODE0NTczNVowGzEZ
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+CX66ucPLd4QJitUy39LZjMlC0YxTZUry
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/alt-9-cert.pem b/test/fixtures/x509-escaping/alt-9-cert.pem
new file mode 100644
index 00000000000000..660e65b8ed7ebd
--- /dev/null
+++ b/test/fixtures/x509-escaping/alt-9-cert.pem
@@ -0,0 +1,28 @@
+-----BEGIN CERTIFICATE-----
+MIIExDCCAqygAwIBAgIBATANBgkqhkiG9w0BAQsFADAbMRkwFwYDVQQDExBldmls
+LmV4YW1wbGUuY29tMB4XDTIxMTIyMDE0NTczNVoXDTMxMTIxODE0NTczNVowGzEZ
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+/7wXhGudHCwm6j2H5/tbsREeYInl3mv4
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/create-certs.js b/test/fixtures/x509-escaping/create-certs.js
new file mode 100644
index 00000000000000..b84547e1d0aef9
--- /dev/null
+++ b/test/fixtures/x509-escaping/create-certs.js
@@ -0,0 +1,502 @@
+'use strict';
+
+const asn1 = require('asn1.js');
+const crypto = require('crypto');
+const { writeFileSync } = require('fs');
+const rfc5280 = require('asn1.js-rfc5280');
+const BN = asn1.bignum;
+
+const oid = {
+  commonName: [2, 5, 4, 3],
+  countryName: [2, 5, 4, 6],
+  localityName: [2, 5, 4, 7],
+  rsaEncryption: [1, 2, 840, 113549, 1, 1, 1],
+  sha256WithRSAEncryption: [1, 2, 840, 113549, 1, 1, 11],
+  xmppAddr: [1, 3, 6, 1, 5, 5, 7, 8, 5],
+  srvName: [1, 3, 6, 1, 5, 5, 7, 8, 7],
+  ocsp: [1, 3, 6, 1, 5, 5, 7, 48, 1],
+  caIssuers: [1, 3, 6, 1, 5, 5, 7, 48, 2],
+  privateUnrecognized: [1, 3, 9999, 12, 34]
+};
+
+const digest = 'SHA256';
+
+const { privateKey, publicKey } = crypto.generateKeyPairSync('rsa', {
+  modulusLength: 4096,
+  publicKeyEncoding: {
+    type: 'pkcs1',
+    format: 'der'
+  }
+});
+
+writeFileSync('server-key.pem', privateKey.export({
+  type: 'pkcs8',
+  format: 'pem'
+}));
+
+const now = Date.now();
+const days = 3650;
+
+function utilType(name, fn) {
+  return asn1.define(name, function() {
+    this[fn]();
+  });
+}
+
+const Null_ = utilType('Null_', 'null_');
+const null_ = Null_.encode('der');
+
+const IA5String = utilType('IA5String', 'ia5str');
+const PrintableString = utilType('PrintableString', 'printstr');
+const UTF8String = utilType('UTF8String', 'utf8str');
+
+const subjectCommonName = PrintableString.encode('evil.example.com', 'der');
+
+const sans = [
+  { type: 'dNSName', value: 'good.example.com, DNS:evil.example.com' },
+  { type: 'uniformResourceIdentifier', value: 'http://example.com/' },
+  { type: 'uniformResourceIdentifier', value: 'http://example.com/?a=b&c=d' },
+  { type: 'uniformResourceIdentifier', value: 'http://example.com/a,b' },
+  { type: 'uniformResourceIdentifier', value: 'http://example.com/a%2Cb' },
+  {
+    type: 'uniformResourceIdentifier',
+    value: 'http://example.com/a, DNS:good.example.com'
+  },
+  { type: 'dNSName', value: Buffer.from('exämple.com', 'latin1') },
+  { type: 'dNSName', value: '"evil.example.com"' },
+  { type: 'iPAddress', value: Buffer.from('08080808', 'hex') },
+  { type: 'iPAddress', value: Buffer.from('08080404', 'hex') },
+  { type: 'iPAddress', value: Buffer.from('0008080404', 'hex') },
+  { type: 'iPAddress', value: Buffer.from('000102030405', 'hex') },
+  {
+    type: 'iPAddress',
+    value: Buffer.from('0a0b0c0d0e0f0000000000007a7b7c7d', 'hex')
+  },
+  { type: 'rfc822Name', value: 'foo@example.com' },
+  { type: 'rfc822Name', value: 'foo@example.com, DNS:good.example.com' },
+  {
+    type: 'directoryName',
+    value: {
+      type: 'rdnSequence',
+      value: [
+        [
+          {
+            type: oid.countryName,
+            value: PrintableString.encode('DE', 'der')
+          }
+        ],
+        [
+          {
+            type: oid.localityName,
+            value: UTF8String.encode('Hannover', 'der')
+          }
+        ]
+      ]
+    }
+  },
+  {
+    type: 'directoryName',
+    value: {
+      type: 'rdnSequence',
+      value: [
+        [
+          {
+            type: oid.countryName,
+            value: PrintableString.encode('DE', 'der')
+          }
+        ],
+        [
+          {
+            type: oid.localityName,
+            value: UTF8String.encode('München', 'der')
+          }
+        ]
+      ]
+    }
+  },
+  {
+    type: 'directoryName',
+    value: {
+      type: 'rdnSequence',
+      value: [
+        [
+          {
+            type: oid.countryName,
+            value: PrintableString.encode('DE', 'der')
+          }
+        ],
+        [
+          {
+            type: oid.localityName,
+            value: UTF8String.encode('Berlin, DNS:good.example.com', 'der')
+          }
+        ]
+      ]
+    }
+  },
+  {
+    type: 'directoryName',
+    value: {
+      type: 'rdnSequence',
+      value: [
+        [
+          {
+            type: oid.countryName,
+            value: PrintableString.encode('DE', 'der')
+          }
+        ],
+        [
+          {
+            type: oid.localityName,
+            value: UTF8String.encode('Berlin, DNS:good.example.com\0evil.example.com', 'der')
+          }
+        ]
+      ]
+    }
+  },
+  {
+    type: 'directoryName',
+    value: {
+      type: 'rdnSequence',
+      value: [
+        [
+          {
+            type: oid.countryName,
+            value: PrintableString.encode('DE', 'der')
+          }
+        ],
+        [
+          {
+            type: oid.localityName,
+            value: UTF8String.encode(
+              'Berlin, DNS:good.example.com\\\0evil.example.com', 'der')
+          }
+        ]
+      ]
+    }
+  },
+  {
+    type: 'directoryName',
+    value: {
+      type: 'rdnSequence',
+      value: [
+        [
+          {
+            type: oid.countryName,
+            value: PrintableString.encode('DE', 'der')
+          }
+        ],
+        [
+          {
+            type: oid.localityName,
+            value: UTF8String.encode('Berlin\r\n', 'der')
+          }
+        ]
+      ]
+    }
+  },
+  {
+    type: 'directoryName',
+    value: {
+      type: 'rdnSequence',
+      value: [
+        [
+          {
+            type: oid.countryName,
+            value: PrintableString.encode('DE', 'der')
+          }
+        ],
+        [
+          {
+            type: oid.localityName,
+            value: UTF8String.encode('Berlin/CN=good.example.com', 'der')
+          }
+        ]
+      ]
+    }
+  },
+  {
+    type: 'registeredID',
+    value: oid.sha256WithRSAEncryption
+  },
+  {
+    type: 'registeredID',
+    value: oid.privateUnrecognized
+  },
+  {
+    type: 'otherName',
+    value: {
+      'type-id': oid.xmppAddr,
+      value: UTF8String.encode('abc123', 'der')
+    }
+  },
+  {
+    type: 'otherName',
+    value: {
+      'type-id': oid.xmppAddr,
+      value: UTF8String.encode('abc123, DNS:good.example.com', 'der')
+    }
+  },
+  {
+    type: 'otherName',
+    value: {
+      'type-id': oid.xmppAddr,
+      value: UTF8String.encode('good.example.com\0abc123', 'der')
+    }
+  },
+  {
+    type: 'otherName',
+    value: {
+      'type-id': oid.privateUnrecognized,
+      value: UTF8String.encode('abc123', 'der')
+    }
+  },
+  {
+    type: 'otherName',
+    value: {
+      'type-id': oid.srvName,
+      value: IA5String.encode('abc123', 'der')
+    }
+  },
+  {
+    type: 'otherName',
+    value: {
+      'type-id': oid.srvName,
+      value: UTF8String.encode('abc123', 'der')
+    }
+  },
+  {
+    type: 'otherName',
+    value: {
+      'type-id': oid.srvName,
+      value: IA5String.encode('abc\0def', 'der')
+    }
+  }
+];
+
+for (let i = 0; i < sans.length; i++) {
+  const san = sans[i];
+
+  const tbs = {
+    version: 'v3',
+    serialNumber: new BN('01', 16),
+    signature: {
+      algorithm: oid.sha256WithRSAEncryption,
+      parameters: null_
+    },
+    issuer: {
+      type: 'rdnSequence',
+      value: [
+        [
+          { type: oid.commonName, value: subjectCommonName }
+        ]
+      ]
+    },
+    validity: {
+      notBefore: { type: 'utcTime', value: now },
+      notAfter: { type: 'utcTime', value: now + days * 86400000 }
+    },
+    subject: {
+      type: 'rdnSequence',
+      value: [
+        [
+          { type: oid.commonName, value: subjectCommonName }
+        ]
+      ]
+    },
+    subjectPublicKeyInfo: {
+      algorithm: {
+        algorithm: oid.rsaEncryption,
+        parameters: null_
+      },
+      subjectPublicKey: {
+        unused: 0,
+        data: publicKey
+      }
+    },
+    extensions: [
+      {
+        extnID: 'subjectAlternativeName',
+        critical: false,
+        extnValue: [san]
+      }
+    ]
+  };
+
+  // Self-sign the certificate.
+  const tbsDer = rfc5280.TBSCertificate.encode(tbs, 'der');
+  const signature = crypto.createSign(digest).update(tbsDer).sign(privateKey);
+
+  // Construct the signed certificate.
+  const cert = {
+    tbsCertificate: tbs,
+    signatureAlgorithm: {
+      algorithm: oid.sha256WithRSAEncryption,
+      parameters: null_
+    },
+    signature: {
+      unused: 0,
+      data: signature
+    }
+  };
+
+  // Store the signed certificate.
+  const pem = rfc5280.Certificate.encode(cert, 'pem', {
+    label: 'CERTIFICATE'
+  });
+  writeFileSync(`./alt-${i}-cert.pem`, `${pem}\n`);
+}
+
+const infoAccessExtensions = [
+  [
+    {
+      accessMethod: oid.ocsp,
+      accessLocation: {
+        type: 'uniformResourceIdentifier',
+        value: 'http://good.example.com/\nOCSP - URI:http://evil.example.com/',
+      },
+    },
+  ],
+  [
+    {
+      accessMethod: oid.caIssuers,
+      accessLocation: {
+        type: 'uniformResourceIdentifier',
+        value: 'http://ca.example.com/\nOCSP - URI:http://evil.example.com',
+      },
+    },
+    {
+      accessMethod: oid.ocsp,
+      accessLocation: {
+        type: 'dNSName',
+        value: 'good.example.com\nOCSP - URI:http://ca.nodejs.org/ca.cert',
+      },
+    },
+  ],
+  [
+    {
+      accessMethod: oid.privateUnrecognized,
+      accessLocation: {
+        type: 'uniformResourceIdentifier',
+        value: 'http://ca.example.com/',
+      },
+    },
+  ],
+  [
+    {
+      accessMethod: oid.ocsp,
+      accessLocation: {
+        type: 'otherName',
+        value: {
+          'type-id': oid.xmppAddr,
+          value: UTF8String.encode('good.example.com', 'der'),
+        },
+      },
+    },
+    {
+      accessMethod: oid.ocsp,
+      accessLocation: {
+        type: 'otherName',
+        value: {
+          'type-id': oid.privateUnrecognized,
+          value: UTF8String.encode('abc123', 'der')
+        },
+      },
+    },
+    {
+      accessMethod: oid.ocsp,
+      accessLocation: {
+        type: 'otherName',
+        value: {
+          'type-id': oid.srvName,
+          value: IA5String.encode('abc123', 'der')
+        }
+      }
+    },
+  ],
+  [
+    {
+      accessMethod: oid.ocsp,
+      accessLocation: {
+        type: 'otherName',
+        value: {
+          'type-id': oid.xmppAddr,
+          value: UTF8String.encode('good.example.com\0abc123', 'der'),
+        },
+      },
+    },
+  ],
+];
+
+for (let i = 0; i < infoAccessExtensions.length; i++) {
+  const infoAccess = infoAccessExtensions[i];
+
+  const tbs = {
+    version: 'v3',
+    serialNumber: new BN('01', 16),
+    signature: {
+      algorithm: oid.sha256WithRSAEncryption,
+      parameters: null_
+    },
+    issuer: {
+      type: 'rdnSequence',
+      value: [
+        [
+          { type: oid.commonName, value: subjectCommonName }
+        ]
+      ]
+    },
+    validity: {
+      notBefore: { type: 'utcTime', value: now },
+      notAfter: { type: 'utcTime', value: now + days * 86400000 }
+    },
+    subject: {
+      type: 'rdnSequence',
+      value: [
+        [
+          { type: oid.commonName, value: subjectCommonName }
+        ]
+      ]
+    },
+    subjectPublicKeyInfo: {
+      algorithm: {
+        algorithm: oid.rsaEncryption,
+        parameters: null_
+      },
+      subjectPublicKey: {
+        unused: 0,
+        data: publicKey
+      }
+    },
+    extensions: [
+      {
+        extnID: 'authorityInformationAccess',
+        critical: false,
+        extnValue: infoAccess
+      }
+    ]
+  };
+
+  // Self-sign the certificate.
+  const tbsDer = rfc5280.TBSCertificate.encode(tbs, 'der');
+  const signature = crypto.createSign(digest).update(tbsDer).sign(privateKey);
+
+  // Construct the signed certificate.
+  const cert = {
+    tbsCertificate: tbs,
+    signatureAlgorithm: {
+      algorithm: oid.sha256WithRSAEncryption,
+      parameters: null_
+    },
+    signature: {
+      unused: 0,
+      data: signature
+    }
+  };
+
+  // Store the signed certificate.
+  const pem = rfc5280.Certificate.encode(cert, 'pem', {
+    label: 'CERTIFICATE'
+  });
+  writeFileSync(`./info-${i}-cert.pem`, `${pem}\n`);
+}
diff --git a/test/fixtures/x509-escaping/google/intermediate.pem b/test/fixtures/x509-escaping/google/intermediate.pem
new file mode 100644
index 00000000000000..9d2aeb32c4e5e5
--- /dev/null
+++ b/test/fixtures/x509-escaping/google/intermediate.pem
@@ -0,0 +1,11 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/google/key.pem b/test/fixtures/x509-escaping/google/key.pem
new file mode 100644
index 00000000000000..102a9d8816cd63
--- /dev/null
+++ b/test/fixtures/x509-escaping/google/key.pem
@@ -0,0 +1,5 @@
+-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgaNbpDxJET5xVHxd/
+ig5x2u2KUIe0jaCVWqarpIN/582hRANCAAR7DaOQvpvA47q2XxjMqxJVf/FvZm2f
+tiFRXNJMe/fhSlDh2CybdkFIw2mE5g4ShW5UBJe+sohqy5V9WRkYtM/B
+-----END PRIVATE KEY-----
diff --git a/test/fixtures/x509-escaping/google/leaf0.pem b/test/fixtures/x509-escaping/google/leaf0.pem
new file mode 100644
index 00000000000000..ce19dc96994ac0
--- /dev/null
+++ b/test/fixtures/x509-escaping/google/leaf0.pem
@@ -0,0 +1,10 @@
+-----BEGIN CERTIFICATE-----
+MIIBajCCARCgAwIBAgIBAzAKBggqhkjOPQQDAjAXMRUwEwYDVQQDEwxJbnRlcm1l
+ZGlhdGUwIBcNMDAwMTAxMDAwMDAwWhgPMjA5OTAxMDEwMDAwMDBaMA8xDTALBgNV
+BAMTBExlYWYwWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAAR7DaOQvpvA47q2XxjM
+qxJVf/FvZm2ftiFRXNJMe/fhSlDh2CybdkFIw2mE5g4ShW5UBJe+sohqy5V9WRkY
+tM/Bo1MwUTAMBgNVHRMBAf8EAjAAMB8GA1UdIwQYMBaAFCUZxhtiiFordL5cZ6oJ
+OLgssd4tMCAGA1UdEQQZMBeCFWJsYWguYXR0YWNrZXIuZXhhbXBsZTAKBggqhkjO
+PQQDAgNIADBFAiEA4NgHDxVrBjNW+So4MrRZMwDknvjRaBsB4j2IwVRKl4sCIDpg
+Bhm4ZdHwlUYrALkXa3dFBy8kXBkVumY7UJpbB2mO
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/google/leaf1.pem b/test/fixtures/x509-escaping/google/leaf1.pem
new file mode 100644
index 00000000000000..0b45056656cab1
--- /dev/null
+++ b/test/fixtures/x509-escaping/google/leaf1.pem
@@ -0,0 +1,10 @@
+-----BEGIN CERTIFICATE-----
+MIIBdTCCARygAwIBAgIBBDAKBggqhkjOPQQDAjAXMRUwEwYDVQQDEwxJbnRlcm1l
+ZGlhdGUwIBcNMDAwMTAxMDAwMDAwWhgPMjA5OTAxMDEwMDAwMDBaMA8xDTALBgNV
+BAMTBExlYWYwWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAAR7DaOQvpvA47q2XxjM
+qxJVf/FvZm2ftiFRXNJMe/fhSlDh2CybdkFIw2mE5g4ShW5UBJe+sohqy5V9WRkY
+tM/Bo18wXTAMBgNVHRMBAf8EAjAAMB8GA1UdIwQYMBaAFCUZxhtiiFordL5cZ6oJ
+OLgssd4tMCwGA1UdEQQlMCOCCm5vZGVqcy5vcmeCFWJsYWguYXR0YWNrZXIuZXhh
+bXBsZTAKBggqhkjOPQQDAgNHADBEAiAOFFOCfA6c/iZWxbDn5QMjNdtZbtJPBcRv
+uEgSqWrGTAIgK5RK0xGK8UZb2aM2VjGNTYozlcwKaLgQukA+UnKrrJg=
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/google/leaf2.pem b/test/fixtures/x509-escaping/google/leaf2.pem
new file mode 100644
index 00000000000000..9cf03fae7d2ae6
--- /dev/null
+++ b/test/fixtures/x509-escaping/google/leaf2.pem
@@ -0,0 +1,10 @@
+-----BEGIN CERTIFICATE-----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==
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/google/leaf3.pem b/test/fixtures/x509-escaping/google/leaf3.pem
new file mode 100644
index 00000000000000..55a64fdc898929
--- /dev/null
+++ b/test/fixtures/x509-escaping/google/leaf3.pem
@@ -0,0 +1,10 @@
+-----BEGIN CERTIFICATE-----
+MIIBZzCCAQ2gAwIBAgIBBjAKBggqhkjOPQQDAjAXMRUwEwYDVQQDEwxJbnRlcm1l
+ZGlhdGUwIBcNMDAwMTAxMDAwMDAwWhgPMjA5OTAxMDEwMDAwMDBaMA8xDTALBgNV
+BAMTBExlYWYwWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAAR7DaOQvpvA47q2XxjM
+qxJVf/FvZm2ftiFRXNJMe/fhSlDh2CybdkFIw2mE5g4ShW5UBJe+sohqy5V9WRkY
+tM/Bo1AwTjAMBgNVHRMBAf8EAjAAMB8GA1UdIwQYMBaAFCUZxhtiiFordL5cZ6oJ
+OLgssd4tMB0GA1UdEQQWMBSGEmh0dHBzOi8vbm9kZWpzLm9yZzAKBggqhkjOPQQD
+AgNIADBFAiEArZgaxFBuPYFWCXeFTkXhV57MKxG/tIJ2Z3Wzts2Im7QCICoukuRf
+EsQN7g6h30fRuLOIdbfCCduc7YVpkkSlwe99
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/google/leaf4.pem b/test/fixtures/x509-escaping/google/leaf4.pem
new file mode 100644
index 00000000000000..668a659f45b540
--- /dev/null
+++ b/test/fixtures/x509-escaping/google/leaf4.pem
@@ -0,0 +1,10 @@
+-----BEGIN CERTIFICATE-----
+MIIBdTCCARugAwIBAgIBBzAKBggqhkjOPQQDAjAXMRUwEwYDVQQDEwxJbnRlcm1l
+ZGlhdGUwIBcNMDAwMTAxMDAwMDAwWhgPMjA5OTAxMDEwMDAwMDBaMDwxHzAdBgNV
+BAsMFm9yZyB1bml0CkNOPW5vZGVqcy5vcmcxGTAXBgNVBAMTEGF0dGFja2VyLmV4
+YW1wbGUwWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAAR7DaOQvpvA47q2XxjMqxJV
+f/FvZm2ftiFRXNJMe/fhSlDh2CybdkFIw2mE5g4ShW5UBJe+sohqy5V9WRkYtM/B
+ozEwLzAMBgNVHRMBAf8EAjAAMB8GA1UdIwQYMBaAFCUZxhtiiFordL5cZ6oJOLgs
+sd4tMAoGCCqGSM49BAMCA0gAMEUCIQCpchwik2NT0v8ifDT8aMqOLv5YwqB7oeOu
+LincYQYMagIgZc2U7DBrdEAWNfuAJx4I+ZkluIcswcdnOhbriOrTSHg=
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/google/root.pem b/test/fixtures/x509-escaping/google/root.pem
new file mode 100644
index 00000000000000..68eb00ae862fbb
--- /dev/null
+++ b/test/fixtures/x509-escaping/google/root.pem
@@ -0,0 +1,9 @@
+-----BEGIN CERTIFICATE-----
+MIIBQTCB56ADAgECAgEBMAoGCCqGSM49BAMCMA8xDTALBgNVBAMTBFJvb3QwIBcN
+MDAwMTAxMDAwMDAwWhgPMjA5OTAxMDEwMDAwMDBaMA8xDTALBgNVBAMTBFJvb3Qw
+WTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAAR7DaOQvpvA47q2XxjMqxJVf/FvZm2f
+tiFRXNJMe/fhSlDh2CybdkFIw2mE5g4ShW5UBJe+sohqy5V9WRkYtM/BozIwMDAP
+BgNVHRMBAf8EBTADAQH/MB0GA1UdDgQWBBQlGcYbYohaK3S+XGeqCTi4LLHeLTAK
+BggqhkjOPQQDAgNJADBGAiEA+Y5oEpcG6aRK5qQFLYRi2FrOSSLF1/dI4HtBh0mk
+GFoCIQD1DpNg6m5ZaogRW1mY1wmR5HFIr3gG8PYDRimQogXUxg==
+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/info-0-cert.pem b/test/fixtures/x509-escaping/info-0-cert.pem
new file mode 100644
index 00000000000000..6872b9870a6cab
--- /dev/null
+++ b/test/fixtures/x509-escaping/info-0-cert.pem
@@ -0,0 +1,30 @@
+-----BEGIN CERTIFICATE-----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+bXBsZS5jb20vCk9DU1AgLSBVUkk6aHR0cDovL2V2aWwuZXhhbXBsZS5jb20vMA0G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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/info-1-cert.pem b/test/fixtures/x509-escaping/info-1-cert.pem
new file mode 100644
index 00000000000000..05247873d85981
--- /dev/null
+++ b/test/fixtures/x509-escaping/info-1-cert.pem
@@ -0,0 +1,31 @@
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/info-2-cert.pem b/test/fixtures/x509-escaping/info-2-cert.pem
new file mode 100644
index 00000000000000..06212d4e12a5da
--- /dev/null
+++ b/test/fixtures/x509-escaping/info-2-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/info-3-cert.pem b/test/fixtures/x509-escaping/info-3-cert.pem
new file mode 100644
index 00000000000000..1825949bd38193
--- /dev/null
+++ b/test/fixtures/x509-escaping/info-3-cert.pem
@@ -0,0 +1,30 @@
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/info-4-cert.pem b/test/fixtures/x509-escaping/info-4-cert.pem
new file mode 100644
index 00000000000000..8f1e69afec7510
--- /dev/null
+++ b/test/fixtures/x509-escaping/info-4-cert.pem
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----
diff --git a/test/fixtures/x509-escaping/package.json b/test/fixtures/x509-escaping/package.json
new file mode 100644
index 00000000000000..37d9f2a9385c46
--- /dev/null
+++ b/test/fixtures/x509-escaping/package.json
@@ -0,0 +1,12 @@
+{
+  "name": "x509-escaping",
+  "version": "1.0.0",
+  "description": "create certificates for x509-escaping test",
+  "main": "createCert.js",
+  "license": "SEE LICENSE IN ../../../LICENSE",
+  "private": true,
+  "dependencies": {
+    "asn1.js": "^5.4.1",
+    "asn1.js-rfc5280": "^3.0.0"
+  }
+}
diff --git a/test/fixtures/x509-escaping/server-key.pem b/test/fixtures/x509-escaping/server-key.pem
new file mode 100644
index 00000000000000..db1d2652d0b76d
--- /dev/null
+++ b/test/fixtures/x509-escaping/server-key.pem
@@ -0,0 +1,52 @@
+-----BEGIN PRIVATE KEY-----
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+XvGkKn5j9RAZcwXrEXMDnhZLEZZ2qBj0C2El71hyBS0ysBnRyWNwR1dcSgx1sJ8H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+-----END PRIVATE KEY-----
diff --git a/test/parallel/test-tls-0-dns-altname.js b/test/parallel/test-tls-0-dns-altname.js
index 4bc87e44cb60c1..e5cb8e3d487af1 100644
--- a/test/parallel/test-tls-0-dns-altname.js
+++ b/test/parallel/test-tls-0-dns-altname.js
@@ -44,7 +44,7 @@ const server = tls.createServer({
   }, common.mustCall(() => {
     const cert = c.getPeerCertificate();
     assert.strictEqual(cert.subjectaltname,
-                       'DNS:good.example.org\0.evil.example.com, ' +
+                       'DNS:"good.example.org\\u0000.evil.example.com", ' +
                            'DNS:just-another.example.com, ' +
                            'IP Address:8.8.8.8, ' +
                            'IP Address:8.8.4.4, ' +
diff --git a/test/parallel/test-x509-escaping.js b/test/parallel/test-x509-escaping.js
new file mode 100644
index 00000000000000..5904e01e43f481
--- /dev/null
+++ b/test/parallel/test-x509-escaping.js
@@ -0,0 +1,338 @@
+'use strict';
+
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+const assert = require('assert');
+const { X509Certificate } = require('crypto');
+const tls = require('tls');
+const fixtures = require('../common/fixtures');
+
+const { hasOpenSSL3 } = common;
+
+// Test that all certificate chains provided by the reporter are rejected.
+{
+  const rootPEM = fixtures.readSync('x509-escaping/google/root.pem');
+  const intermPEM = fixtures.readSync('x509-escaping/google/intermediate.pem');
+  const keyPEM = fixtures.readSync('x509-escaping/google/key.pem');
+
+  const numLeaves = 5;
+
+  for (let i = 0; i < numLeaves; i++) {
+    // TODO(tniessen): this test case requires proper handling of URI SANs,
+    // which node currently does not implement.
+    if (i === 3) continue;
+
+    const name = `x509-escaping/google/leaf${i}.pem`;
+    const leafPEM = fixtures.readSync(name, 'utf8');
+
+    const server = tls.createServer({
+      key: keyPEM,
+      cert: leafPEM + intermPEM,
+    }, common.mustNotCall()).listen(common.mustCall(() => {
+      const { port } = server.address();
+      const socket = tls.connect(port, {
+        ca: rootPEM,
+        servername: 'nodejs.org',
+      }, common.mustNotCall());
+      socket.on('error', common.mustCall());
+    })).unref();
+  }
+}
+
+// Test escaping rules for subject alternative names.
+{
+  const expectedSANs = [
+    'DNS:"good.example.com\\u002c DNS:evil.example.com"',
+    // URIs should not require escaping.
+    'URI:http://example.com/',
+    'URI:http://example.com/?a=b&c=d',
+    // Unless they contain commas.
+    'URI:"http://example.com/a\\u002cb"',
+    // Percent encoding should not require escaping.
+    'URI:http://example.com/a%2Cb',
+    // Malicious attempts should be escaped.
+    'URI:"http://example.com/a\\u002c DNS:good.example.com"',
+    // Non-ASCII characters in DNS names should be treated as Latin-1.
+    'DNS:"ex\\u00e4mple.com"',
+    // It should not be possible to cause unescaping without escaping.
+    'DNS:"\\"evil.example.com\\""',
+    // IPv4 addresses should be represented as usual.
+    'IP Address:8.8.8.8',
+    'IP Address:8.8.4.4',
+    // For backward-compatibility, include invalid IP address lengths.
+    hasOpenSSL3 ? 'IP Address:<invalid length=5>' : 'IP Address:<invalid>',
+    hasOpenSSL3 ? 'IP Address:<invalid length=6>' : 'IP Address:<invalid>',
+    // IPv6 addresses are represented as OpenSSL does.
+    'IP Address:A0B:C0D:E0F:0:0:0:7A7B:7C7D',
+    // Regular email addresses don't require escaping.
+    'email:foo@example.com',
+    // ... but should be escaped if they contain commas.
+    'email:"foo@example.com\\u002c DNS:good.example.com"',
+    'DirName:/C=DE/L=Hannover',
+    // TODO(tniessen): support UTF8 in DirName
+    'DirName:"/C=DE/L=M\\\\xC3\\\\xBCnchen"',
+    'DirName:"/C=DE/L=Berlin\\u002c DNS:good.example.com"',
+    'DirName:"/C=DE/L=Berlin\\u002c DNS:good.example.com\\\\x00' +
+      'evil.example.com"',
+    'DirName:"/C=DE/L=Berlin\\u002c DNS:good.example.com\\\\\\\\x00' +
+      'evil.example.com"',
+    // These next two tests might be surprising. OpenSSL applies its own rules
+    // first, which introduce backslashes, which activate node's escaping.
+    // Unfortunately, there are also differences between OpenSSL 1.1.1 and 3.0.
+    'DirName:"/C=DE/L=Berlin\\\\x0D\\\\x0A"',
+    hasOpenSSL3 ?
+      'DirName:"/C=DE/L=Berlin\\\\/CN=good.example.com"' :
+      'DirName:/C=DE/L=Berlin/CN=good.example.com',
+    // TODO(tniessen): even OIDs that are well-known (such as the following,
+    // which is sha256WithRSAEncryption) should be represented numerically only.
+    'Registered ID:sha256WithRSAEncryption',
+    // This is an OID that will likely never be assigned to anything, thus
+    // OpenSSL should not know it.
+    'Registered ID:1.3.9999.12.34',
+    hasOpenSSL3 ?
+      'othername: XmppAddr::abc123' :
+      'othername:<unsupported>',
+    hasOpenSSL3 ?
+      'othername:" XmppAddr::abc123\\u002c DNS:good.example.com"' :
+      'othername:<unsupported>',
+    hasOpenSSL3 ?
+      'othername:" XmppAddr::good.example.com\\u0000abc123"' :
+      'othername:<unsupported>',
+    // This is unsupported because the OID is not recognized.
+    'othername:<unsupported>',
+    hasOpenSSL3 ? 'othername: SRVName::abc123' : 'othername:<unsupported>',
+    // This is unsupported because it is an SRVName with a UTF8String value,
+    // which is not allowed for SRVName.
+    'othername:<unsupported>',
+    hasOpenSSL3 ?
+      'othername:" SRVName::abc\\u0000def"' :
+      'othername:<unsupported>',
+  ];
+
+  const serverKey = fixtures.readSync('x509-escaping/server-key.pem', 'utf8');
+
+  for (let i = 0; i < expectedSANs.length; i++) {
+    const pem = fixtures.readSync(`x509-escaping/alt-${i}-cert.pem`, 'utf8');
+
+    // Test the subjectAltName property of the X509Certificate API.
+    const cert = new X509Certificate(pem);
+    assert.strictEqual(cert.subjectAltName, expectedSANs[i]);
+
+    // Test that the certificate obtained by checkServerIdentity has the correct
+    // subjectaltname property.
+    const server = tls.createServer({
+      key: serverKey,
+      cert: pem,
+    }, common.mustCall((conn) => {
+      conn.destroy();
+      server.close();
+    })).listen(common.mustCall(() => {
+      const { port } = server.address();
+      tls.connect(port, {
+        ca: pem,
+        servername: 'example.com',
+        checkServerIdentity: (hostname, peerCert) => {
+          assert.strictEqual(hostname, 'example.com');
+          assert.strictEqual(peerCert.subjectaltname, expectedSANs[i]);
+        },
+      }, common.mustCall());
+    }));
+  }
+}
+
+// Test escaping rules for authority info access.
+{
+  const expectedInfoAccess = [
+    {
+      text: 'OCSP - URI:"http://good.example.com/\\u000a' +
+            'OCSP - URI:http://evil.example.com/"',
+      legacy: {
+        'OCSP - URI': [
+          'http://good.example.com/\nOCSP - URI:http://evil.example.com/',
+        ],
+      },
+    },
+    {
+      text: 'CA Issuers - URI:"http://ca.example.com/\\u000a' +
+            'OCSP - URI:http://evil.example.com"\n' +
+            'OCSP - DNS:"good.example.com\\u000a' +
+            'OCSP - URI:http://ca.nodejs.org/ca.cert"',
+      legacy: {
+        'CA Issuers - URI': [
+          'http://ca.example.com/\nOCSP - URI:http://evil.example.com',
+        ],
+        'OCSP - DNS': [
+          'good.example.com\nOCSP - URI:http://ca.nodejs.org/ca.cert',
+        ],
+      },
+    },
+    {
+      text: '1.3.9999.12.34 - URI:http://ca.example.com/',
+      legacy: {
+        '1.3.9999.12.34 - URI': [
+          'http://ca.example.com/',
+        ],
+      },
+    },
+    hasOpenSSL3 ? {
+      text: 'OCSP - othername: XmppAddr::good.example.com\n' +
+            'OCSP - othername:<unsupported>\n' +
+            'OCSP - othername: SRVName::abc123',
+      legacy: {
+        'OCSP - othername': [
+          ' XmppAddr::good.example.com',
+          '<unsupported>',
+          ' SRVName::abc123',
+        ],
+      },
+    } : {
+      text: 'OCSP - othername:<unsupported>\n' +
+            'OCSP - othername:<unsupported>\n' +
+            'OCSP - othername:<unsupported>',
+      legacy: {
+        'OCSP - othername': [
+          '<unsupported>',
+          '<unsupported>',
+          '<unsupported>',
+        ],
+      },
+    },
+    hasOpenSSL3 ? {
+      text: 'OCSP - othername:" XmppAddr::good.example.com\\u0000abc123"',
+      legacy: {
+        'OCSP - othername': [
+          ' XmppAddr::good.example.com\0abc123',
+        ],
+      },
+    } : {
+      text: 'OCSP - othername:<unsupported>',
+      legacy: {
+        'OCSP - othername': [
+          '<unsupported>',
+        ],
+      },
+    },
+  ];
+
+  const serverKey = fixtures.readSync('x509-escaping/server-key.pem', 'utf8');
+
+  for (let i = 0; i < expectedInfoAccess.length; i++) {
+    const pem = fixtures.readSync(`x509-escaping/info-${i}-cert.pem`, 'utf8');
+    const expected = expectedInfoAccess[i];
+
+    // Test the subjectAltName property of the X509Certificate API.
+    const cert = new X509Certificate(pem);
+    assert.strictEqual(cert.infoAccess,
+                       `${expected.text}${hasOpenSSL3 ? '' : '\n'}`);
+
+    // Test that the certificate obtained by checkServerIdentity has the correct
+    // subjectaltname property.
+    const server = tls.createServer({
+      key: serverKey,
+      cert: pem,
+    }, common.mustCall((conn) => {
+      conn.destroy();
+      server.close();
+    })).listen(common.mustCall(() => {
+      const { port } = server.address();
+      tls.connect(port, {
+        ca: pem,
+        servername: 'example.com',
+        checkServerIdentity: (hostname, peerCert) => {
+          assert.strictEqual(hostname, 'example.com');
+          assert.deepStrictEqual(peerCert.infoAccess,
+                                 Object.assign(Object.create(null),
+                                               expected.legacy));
+        },
+      }, common.mustCall());
+    }));
+  }
+}
+
+// The internal parsing logic must match the JSON specification exactly.
+{
+  // This list is partially based on V8's own JSON tests.
+  const invalidJSON = [
+    '"\\a invalid escape"',
+    '"\\v invalid escape"',
+    '"\\\' invalid escape"',
+    '"\\x42 invalid escape"',
+    '"\\u202 invalid escape"',
+    '"\\012 invalid escape"',
+    '"Unterminated string',
+    '"Unterminated string\\"',
+    '"Unterminated string\\\\\\"',
+    '"\u0000 control character"',
+    '"\u001e control character"',
+    '"\u001f control character"',
+  ];
+
+  for (const invalidStringLiteral of invalidJSON) {
+    // Usually, checkServerIdentity returns an error upon verification failure.
+    // In this case, however, it should throw an error since this is not a
+    // verification error. Node.js itself will never produce invalid JSON string
+    // literals, so this can only happen when users construct invalid subject
+    // alternative name strings (that do not follow escaping rules).
+    assert.throws(() => {
+      tls.checkServerIdentity('example.com', {
+        subjectaltname: `DNS:${invalidStringLiteral}`,
+      });
+    }, {
+      code: 'ERR_TLS_CERT_ALTNAME_FORMAT',
+      message: 'Invalid subject alternative name string'
+    });
+  }
+}
+
+// While node does not produce commas within SAN entries, it should parse them
+// correctly (i.e., not simply split at commas).
+{
+  // Regardless of the quotes, splitting this SAN string at commas would
+  // cause checkServerIdentity to see 'DNS:b.example.com' and thus to accept
+  // the certificate for b.example.com.
+  const san = 'DNS:"a.example.com, DNS:b.example.com, DNS:c.example.com"';
+
+  // This is what node used to do, and which is not correct!
+  const hostname = 'b.example.com';
+  assert.strictEqual(san.split(', ')[1], `DNS:${hostname}`);
+
+  // The new implementation should parse the string correctly.
+  const err = tls.checkServerIdentity(hostname, { subjectaltname: san });
+  assert(err);
+  assert.strictEqual(err.code, 'ERR_TLS_CERT_ALTNAME_INVALID');
+  assert.strictEqual(err.message, 'Hostname/IP does not match certificate\'s ' +
+                                  'altnames: Host: b.example.com. is not in ' +
+                                  'the cert\'s altnames: DNS:"a.example.com, ' +
+                                  'DNS:b.example.com, DNS:c.example.com"');
+}
+
+// The subject MUST be ignored if a dNSName subject alternative name exists.
+{
+  const key = fixtures.readKey('incorrect_san_correct_subject-key.pem');
+  const cert = fixtures.readKey('incorrect_san_correct_subject-cert.pem');
+
+  // The hostname is the CN, but not a SAN entry.
+  const servername = 'good.example.com';
+  const certX509 = new X509Certificate(cert);
+  assert.strictEqual(certX509.subject, `CN=${servername}`);
+  assert.strictEqual(certX509.subjectAltName, 'DNS:evil.example.com');
+
+  // Try connecting to a server that uses the self-signed certificate.
+  const server = tls.createServer({ key, cert }, common.mustNotCall());
+  server.listen(common.mustCall(() => {
+    const { port } = server.address();
+    const socket = tls.connect(port, {
+      ca: cert,
+      servername,
+    }, common.mustNotCall());
+    socket.on('error', common.mustCall((err) => {
+      assert.strictEqual(err.code, 'ERR_TLS_CERT_ALTNAME_INVALID');
+      assert.strictEqual(err.message, 'Hostname/IP does not match ' +
+                                      "certificate's altnames: Host: " +
+                                      "good.example.com. is not in the cert's" +
+                                      ' altnames: DNS:evil.example.com');
+    }));
+  })).unref();
+}