Overview
About vulnerability
A vulnerability was discovered in @angular/common when Server-Side Rendering (SSR) and hydration are enabled. The HttpTransferCache utility optimizes hydration by caching outgoing HTTP requests performed during SSR and transferring the cached state to the client-side application via TransferState.
However, the caching mechanism fails to inspect the withCredentials flag or the Cookie header of outgoing requests. As a result, credentialed, user-specific responses may be cached by default in the shared TransferState payload. When these responses are serialized into the HTML, any caching layer (such as a CDN, reverse proxy, or shared server cache) that caches the SSR-rendered HTML page could inadvertently cache and leak one user’s private data to other users, leading to a high-severity information disclosure vulnerability.
Impact
Successful exploitation allows an unauthenticated attacker to obtain sensitive, user-specific information of other authenticated users. This occurs when:
- The SSR-rendered HTML containing the cached private data is stored in a shared cache (e.g., CDN, reverse proxy).
- Subsequent requests for the same page receive the cached HTML containing the first user’s private data.
Attack Preconditions
- SSR and Hydration Enabled: The Angular application must be configured to use Server-Side Rendering and hydration (e.g., using
provideClientHydration()). - Credentialed Requests during SSR: The application must perform HTTP requests that require user-specific authentication (using cookies or
withCredentials: true) during the initial server-side render. - Shared Caching: The application’s HTML responses must be cached by a shared caching layer (CDN, reverse proxy, or server-side cache) without proper cache-control headers to distinguish authenticated users.
Patches
- 22.0.0-rc.2
- 21.2.15
- 20.3.22
- 19.2.23
Details
- Affected product:
- Angular , AngularJS , ng-packagr , nguniversal
- Affected packages:
- @angular/compiler @ 13.4.0 (+866 more)