@angular/common: Information Leak via Default Caching of Credentialed Requests in HttpTransferCache
Date: 2026-06
Affected: npm/@angular/common, npm/@angular/common, npm/@angular/common
Attack vector: info-disclosure
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-50170
CWE: CWE-524

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 r


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