Angular Service Worker EUVD-2026-38274

An information disclosure vulnerability exists in the @angular/service-worker package of the Angular framework. When the Service Worker fetches assets, it preserves metadata (such as headers) from the original request. However, on cross-origin redirects, the Service Worker fails to strip sensitive headers, violating the Fetch redirect algorithm.

This allows a remote attacker to obtain sensitive credentials (e.g., Authorization tokens, Proxy-Authorization credentials, or session cookies) by triggering a cross-origin redirect to an untrusted external origin.

Impact

If an application configured with the Angular Service Worker fetches assets with credential headers (such as Authorization header), and one of those requests is redirected to a different origin, the Service Worker will forward those headers to the new origin. This exposes critical credentials and session identifiers to unauthorized third-party servers.

Attack Preconditions

For this vulnerability to be exploitable:

1. Vulnerable Configuration: The application must utilize the @angular/service-worker package to fetch assets.
2. Credentialed Requests: The application must attach sensitive request headers (like Authorization, Proxy-Authorization, or rely on cookies) to asset-group requests.
3. Redirect Flow: These requests must encounter a cross-origin redirect to an attacker-controlled or untrusted domain.

Patched Versions

• 22.0.1
• 21.2.17
• 20.3.25

Credits

This vulnerability was discovered and reported by CodeMender from Google DeepMind.