GHSA-q6f4-qqrg-jv6x @angular/common: Information Leak via Default Caching of Credentialed Requests in HttpTransferCache

• npm @angular/common: >= 22.0.0-next.0, < 22.0.0-rc.2 → fixed in 22.0.0-rc.2 • npm @angular/common: >= 20.0.0-next.0, < 20.3.22 → fixed in 20.3.22 • npm @angular/common: >= 19.0.0-next.0, < 19.2.23 → fixed in 19.2.23 • npm @angular/common: <= 18.2.14 (no fix yet) • npm @angular/common: >= 21.0.0-next.0, < 21.2.15 → fixed in 21.2.15

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