diff --git a/source/extensions/filters/common/expr/BUILD b/source/extensions/filters/common/expr/BUILD
index 014af08fbb9fb..316c36b05b19d 100644
--- a/source/extensions/filters/common/expr/BUILD
+++ b/source/extensions/filters/common/expr/BUILD
@@ -29,6 +29,7 @@ envoy_cc_library(
     hdrs = ["context.h"],
     deps = [
         "//source/common/grpc:common_lib",
+        "//source/common/http:header_map_lib",
         "//source/common/http:utility_lib",
         "//source/common/stream_info:utility_lib",
         "@com_google_cel_cpp//eval/public:cel_value",
diff --git a/source/extensions/filters/common/expr/context.cc b/source/extensions/filters/common/expr/context.cc
index 6ae0eef652d34..ac5338cb86e9f 100644
--- a/source/extensions/filters/common/expr/context.cc
+++ b/source/extensions/filters/common/expr/context.cc
@@ -1,6 +1,7 @@
 #include "extensions/filters/common/expr/context.h"
 
 #include "common/grpc/common.h"
+#include "common/http/header_map_impl.h"
 #include "common/http/utility.h"
 
 #include "absl/strings/numbers.h"
@@ -80,6 +81,9 @@ absl::optional<CelValue> RequestWrapper::operator[](CelValue key) const {
     } else {
       return CelValue::CreateInt64(info_.bytesReceived());
     }
+  } else if (value == TotalSize) {
+    return CelValue::CreateInt64(info_.bytesReceived() +
+                                 (headers_.value_ ? headers_.value_->byteSize() : 0));
   } else if (value == Duration) {
     auto duration = info_.requestComplete();
     if (duration.has_value()) {
@@ -115,8 +119,6 @@ absl::optional<CelValue> RequestWrapper::operator[](CelValue key) const {
       return convertHeaderEntry(headers_.value_->RequestId());
     } else if (value == UserAgent) {
       return convertHeaderEntry(headers_.value_->UserAgent());
-    } else if (value == TotalSize) {
-      return CelValue::CreateInt64(info_.bytesReceived() + headers_.value_->byteSize());
     }
   }
   return {};
@@ -141,15 +143,17 @@ absl::optional<CelValue> ResponseWrapper::operator[](CelValue key) const {
   } else if (value == Flags) {
     return CelValue::CreateInt64(info_.responseFlags());
   } else if (value == GrpcStatus) {
-    auto const& optional_status =
-        Grpc::Common::getGrpcStatus(*(trailers_.value_), *(headers_.value_), info_);
+    auto const& optional_status = Grpc::Common::getGrpcStatus(
+        trailers_.value_ ? *trailers_.value_ : ConstSingleton<Http::HeaderMapImpl>::get(),
+        headers_.value_ ? *headers_.value_ : ConstSingleton<Http::HeaderMapImpl>::get(), info_);
     if (optional_status.has_value()) {
       return CelValue::CreateInt64(optional_status.value());
     }
     return {};
   } else if (value == TotalSize) {
-    return CelValue::CreateInt64(info_.bytesSent() + headers_.value_->byteSize() +
-                                 trailers_.value_->byteSize());
+    return CelValue::CreateInt64(info_.bytesSent() +
+                                 (headers_.value_ ? headers_.value_->byteSize() : 0) +
+                                 (trailers_.value_ ? trailers_.value_->byteSize() : 0));
   }
   return {};
 }
diff --git a/test/extensions/filters/common/expr/context_test.cc b/test/extensions/filters/common/expr/context_test.cc
index 8768d811a2f1f..549bdd842a530 100644
--- a/test/extensions/filters/common/expr/context_test.cc
+++ b/test/extensions/filters/common/expr/context_test.cc
@@ -32,12 +32,14 @@ TEST(Context, EmptyHeadersAttributes) {
 
 TEST(Context, RequestAttributes) {
   NiceMock<StreamInfo::MockStreamInfo> info;
+  NiceMock<StreamInfo::MockStreamInfo> empty_info;
   Http::TestHeaderMapImpl header_map{
       {":method", "POST"},           {":scheme", "http"},      {":path", "/meow?yes=1"},
       {":authority", "kittens.com"}, {"referer", "dogs.com"},  {"user-agent", "envoy-mobile"},
       {"content-length", "10"},      {"x-request-id", "blah"},
   };
   RequestWrapper request(&header_map, info);
+  RequestWrapper empty_request(nullptr, empty_info);
 
   EXPECT_CALL(info, bytesReceived()).WillRepeatedly(Return(10));
   // "2018-04-03T23:06:09.123Z".
@@ -67,6 +69,12 @@ TEST(Context, RequestAttributes) {
     ASSERT_TRUE(value.value().IsString());
     EXPECT_EQ("http", value.value().StringOrDie().value());
   }
+
+  {
+    auto value = empty_request[CelValue::CreateStringView(Scheme)];
+    EXPECT_FALSE(value.has_value());
+  }
+
   {
     auto value = request[CelValue::CreateStringView(Host)];
     EXPECT_TRUE(value.has_value());
@@ -131,6 +139,14 @@ TEST(Context, RequestAttributes) {
     EXPECT_EQ(138, value.value().Int64OrDie());
   }
 
+  {
+    auto value = empty_request[CelValue::CreateStringView(TotalSize)];
+    EXPECT_TRUE(value.has_value());
+    ASSERT_TRUE(value.value().IsInt64());
+    // this includes the headers size
+    EXPECT_EQ(0, value.value().Int64OrDie());
+  }
+
   {
     auto value = request[CelValue::CreateStringView(Time)];
     EXPECT_TRUE(value.has_value());
@@ -159,12 +175,22 @@ TEST(Context, RequestAttributes) {
     EXPECT_EQ("15ms", absl::FormatDuration(value.value().DurationOrDie()));
   }
 
+  {
+    auto value = empty_request[CelValue::CreateStringView(Duration)];
+    EXPECT_FALSE(value.has_value());
+  }
+
   {
     auto value = request[CelValue::CreateStringView(Protocol)];
     EXPECT_TRUE(value.has_value());
     ASSERT_TRUE(value.value().IsString());
     EXPECT_EQ("HTTP/2", value.value().StringOrDie().value());
   }
+
+  {
+    auto value = empty_request[CelValue::CreateStringView(Protocol)];
+    EXPECT_FALSE(value.has_value());
+  }
 }
 
 TEST(Context, RequestFallbackAttributes) {
@@ -195,12 +221,14 @@ TEST(Context, RequestFallbackAttributes) {
 
 TEST(Context, ResponseAttributes) {
   NiceMock<StreamInfo::MockStreamInfo> info;
+  NiceMock<StreamInfo::MockStreamInfo> empty_info;
   const std::string header_name = "test-header";
   const std::string trailer_name = "test-trailer";
   const std::string grpc_status = "grpc-status";
   Http::TestHeaderMapImpl header_map{{header_name, "a"}};
   Http::TestHeaderMapImpl trailer_map{{trailer_name, "b"}, {grpc_status, "8"}};
   ResponseWrapper response(&header_map, &trailer_map, info);
+  ResponseWrapper empty_response(nullptr, nullptr, empty_info);
 
   EXPECT_CALL(info, responseCode()).WillRepeatedly(Return(404));
   EXPECT_CALL(info, bytesSent()).WillRepeatedly(Return(123));
@@ -230,6 +258,13 @@ TEST(Context, ResponseAttributes) {
     EXPECT_EQ(160, value.value().Int64OrDie());
   }
 
+  {
+    auto value = empty_response[CelValue::CreateStringView(TotalSize)];
+    EXPECT_TRUE(value.has_value());
+    ASSERT_TRUE(value.value().IsInt64());
+    EXPECT_EQ(0, value.value().Int64OrDie());
+  }
+
   {
     auto value = response[CelValue::CreateStringView(Code)];
     EXPECT_TRUE(value.has_value());
@@ -267,18 +302,26 @@ TEST(Context, ResponseAttributes) {
     ASSERT_TRUE(header.value().IsString());
     EXPECT_EQ("b", header.value().StringOrDie().value());
   }
+
   {
     auto value = response[CelValue::CreateStringView(Flags)];
     EXPECT_TRUE(value.has_value());
     ASSERT_TRUE(value.value().IsInt64());
     EXPECT_EQ(0x1, value.value().Int64OrDie());
   }
+
   {
     auto value = response[CelValue::CreateStringView(GrpcStatus)];
     EXPECT_TRUE(value.has_value());
     ASSERT_TRUE(value.value().IsInt64());
     EXPECT_EQ(0x8, value.value().Int64OrDie());
   }
+
+  {
+    auto value = empty_response[CelValue::CreateStringView(GrpcStatus)];
+    EXPECT_FALSE(value.has_value());
+  }
+
   {
     Http::TestHeaderMapImpl header_map{{header_name, "a"}, {grpc_status, "7"}};
     Http::TestHeaderMapImpl trailer_map{{trailer_name, "b"}};