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fix(platform-server): reject protocol-relative paths in resolveUrl #71077

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Merged
atscott merged 1 commit into from
Sep 30, 2026
Merged

fix(platform-server): reject protocol-relative paths in resolveUrl #71077

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38 changes: 32 additions & 6 deletions packages/platform-server/src/url.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,10 @@ export function resolveUrl(
const {allowProtocolRelative = false, allowOriginChange = true} = options;

if (resolved) {
if (isDisallowedProtocolRelative(resolved, allowProtocolRelative)) {
throwProtocolRelativeUrlError(urlStr);
}

if (originUrl && !isSafeOriginChange(resolved, originUrl, urlStr, allowOriginChange)) {
throwSuspiciousUrlError(urlStr);
}
Expand Down Expand Up @@ -102,26 +106,48 @@ export function resolveUrl(
// and we are configured to allow and preserve standard cross-origin protocol-relative requests.
if (urlStr.startsWith('//')) {
if (!allowProtocolRelative) {
throw new RuntimeError(
RuntimeErrorCode.PROTOCOL_RELATIVE_URL_NOT_ALLOWED,
typeof ngDevMode === 'undefined' || ngDevMode
? `Protocol relative URLs are not allowed in this context. URL: ${urlStr}`
: urlStr,
);
throwProtocolRelativeUrlError(urlStr);
}

return new URL(urlStr, origin);
}

resolved = new URL(urlStr, origin);

if (isDisallowedProtocolRelative(resolved, allowProtocolRelative)) {
throwProtocolRelativeUrlError(urlStr);
}

if (!isSafeOriginChange(resolved, originUrl, urlStr, allowOriginChange)) {
throwSuspiciousUrlError(urlStr);
}

return resolved;
}

/**
* Checks if the resolved URL has a disallowed protocol-relative path.
*
* @param resolved The resolved URL.
* @param allowProtocolRelative Whether protocol-relative URLs are allowed.
* @returns True if the URL has a disallowed protocol-relative path, false otherwise.
*/
function isDisallowedProtocolRelative(resolved: URL, allowProtocolRelative: boolean): boolean {
return !allowProtocolRelative && resolved.pathname.startsWith('//');
}

/**
* Throws a protocol-relative URL error indicating that protocol-relative URLs are not allowed.
*/
function throwProtocolRelativeUrlError(urlStr: string): never {
throw new RuntimeError(
RuntimeErrorCode.PROTOCOL_RELATIVE_URL_NOT_ALLOWED,
typeof ngDevMode === 'undefined' || ngDevMode
? `Protocol relative URLs are not allowed in this context. URL: ${urlStr}`
: urlStr,
);
}

/**
* Throws a suspicious URL error indicating a security bypass attempt.
*/
Expand Down
28 changes: 28 additions & 0 deletions packages/platform-server/test/url_spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,34 @@ describe('resolveUrl', () => {
expect(() => resolveUrl(url, 'http://test.com')).toThrowError(/NG05703/);
});

it('should throw on protocol-relative URLs when allowProtocolRelative is false or default', () => {
const urls = [
'//attacker.example/collect',
'///attacker.example/collect',
'/.//attacker.example/collect',
'/..//attacker.example/collect',
'/.\\/attacker.example/collect',
'http://test.com/.//attacker.example/collect',
];

for (const url of urls) {
expect(() => resolveUrl(url, 'http://test.com')).toThrowError(/NG05702/);
}
});

it('should allow protocol-relative URLs when allowProtocolRelative is true', () => {
const url = resolveUrl('//attacker.example/collect', 'http://test.com', {
allowProtocolRelative: true,
});
expect(url.href).toBe('http://attacker.example/collect');
expect(url.origin).toBe('http://attacker.example');

const dotUrl = resolveUrl('/.//attacker.example/collect', 'http://test.com', {
allowProtocolRelative: true,
});
expect(dotUrl.href).toBe('http://test.com//attacker.example/collect');
});

it('should not trim unicode whitespace into protocol-relative URLs', () => {
const urls = ['\u00A0//attacker.example/collect', '\uFEFF//attacker.example/collect'];

Expand Down
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