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Tighten image endpoint path handling #16544

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Merged
matthewp merged 2 commits into from
May 8, 2026
Merged

Tighten image endpoint path handling #16544

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90ae918
Tighten isRemotePath and dev image endpoint origin check
matthewp Apr 30, 2026
87dcb8d
Use \w in regex to satisfy eslint regexp/prefer-w
matthewp Apr 30, 2026
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6 changes: 6 additions & 0 deletions .changeset/image-endpoint-cleanup.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
---
'astro': patch
'@astrojs/internal-helpers': patch
---

Tightens `isRemotePath()` to reject control characters after a leading slash and fixes the dev image endpoint origin check
2 changes: 1 addition & 1 deletion packages/astro/src/assets/endpoint/dev.ts
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Expand Up @@ -55,7 +55,7 @@ async function loadLocalImage(src: string, url: URL) {
const sourceUrl = new URL(src, url.origin);
// This is only allowed if this is the same origin
if (sourceUrl.origin !== url.origin) {
returnValue = undefined;
return undefined;
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@matthewp matthewp Apr 30, 2026

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this was dead-code before, always would try to load the remote image.

}
return loadRemoteImage(sourceUrl);
}
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4 changes: 2 additions & 2 deletions packages/internal-helpers/src/path.ts
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Expand Up @@ -148,9 +148,9 @@ export function isRemotePath(src: string) {
return false;
}

// Check for Unix absolute path (starts with / but not // or /\)
// Check for Unix absolute path (starts with / followed by a normal path character)
// This needs to be before the backslash check
if (decoded[0] === '/' && decoded[1] !== '/' && decoded[1] !== '\\') {
if (decoded[0] === '/' && /^\/[\w.@-]/.test(decoded)) {
return false;
}

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11 changes: 11 additions & 0 deletions packages/internal-helpers/test/path.test.ts
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Expand Up @@ -78,6 +78,17 @@ describe('isRemotePath', () => {
'\\%0Aexample.com/test',
'\\%0Dexample.com/test',

// CRLF injection in path (control chars after leading slash cause URL parser
// to treat the remainder as a protocol-relative URL)
'/%0d%0a/example.com',
'/%0d%0a/example.com:8080/path',
'/%0a/example.com',
'/%0d/example.com',
'/\r\n/example.com',
'/\n/example.com',
'/\r/example.com',
'/\t/example.com',

// IP addresses
'http://192.168.1.1/test',
'//192.168.1.1/test',
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