@angular/common: Information Leak via Default Caching of Credentialed Requests in HttpTransferCache

@@ -432,7 +432,7 @@ To configure this, update your `angular.json` file as follows:
 You can customize how Angular caches HTTP responses during server‑side rendering (SSR) and reuses them during hydration by configuring `HttpTransferCacheOptions`.  
 This configuration is provided globally using `withHttpTransferCacheOptions` inside `provideClientHydration()`.
 
-By default, `HttpClient` caches all `HEAD` and `GET` requests which don't contain `Authorization`, `Proxy-Authorization`, or `Cookie` headers. You can override those settings by using `withHttpTransferCacheOptions` to the hydration configuration.
+By default, `HttpClient` caches all `HEAD` and `GET` requests which don't contain `Authorization`, `Proxy-Authorization`, or `Cookie` headers and are not sent with `withCredentials`. You can override those settings by using `withHttpTransferCacheOptions` to the hydration configuration.
 
 ```ts
 import {bootstrapApplication} from '@angular/platform-browser';
@@ -487,7 +487,7 @@ Use this only when `POST` requests are **idempotent** and safe to reuse between
 ### `includeRequestsWithAuthHeaders`
 
 Determines whether requests containing `Authorization`, `Proxy‑Authorization`, or `Cookie` headers are eligible for caching.  
-By default, these are excluded to prevent caching user‑specific responses.
+By default, these are excluded to prevent caching user‑specific responses. Requests sent with `withCredentials` are also excluded by default.
 
 ```ts
 withHttpTransferCacheOptions({

@@ -42,7 +42,7 @@ import {HttpParams} from './params';
  *     (for example using GraphQL).
  * @param includeRequestsWithAuthHeaders Enables caching of requests containing `Authorization`,
  *     `Proxy-Authorization`, or `Cookie` headers. By default, these requests are excluded from
- *     caching.
+ *     caching. Requests sent using `withCredentials` are also excluded by default.
  *
  * @see [Configuring the caching options](guide/ssr#configuring-the-caching-options)
  *
@@ -131,6 +131,8 @@ function shouldCacheRequest(req: HttpRequest<unknown>, options: CacheOptions): b
   if (
     !isCacheActive ||
     requestOptions === false ||
+    // Do not cache requests sent with credentials.
+    req.withCredentials ||
     // POST requests are allowed either globally or at request level
     (requestMethod === 'POST' && !globalOptions.includePostRequests && !requestOptions) ||
     (requestMethod !== 'POST' && !ALLOWED_METHODS.includes(requestMethod)) ||

@@ -40,6 +40,7 @@ interface RequestParams {
   observe?: 'body' | 'response';
   transferCache?: {includeHeaders: string[]} | boolean;
   headers?: {[key: string]: string};
+  withCredentials?: boolean;
   body?: RequestBody;
 }
 
@@ -429,6 +430,16 @@ describe('TransferCache', () => {
       makeRequestAndExpectOne('/test-auth', 'foo');
     });
 
+    it('should not cache requests with credentials', async () => {
+      makeRequestAndExpectOne('/test-auth', 'foo', {
+        withCredentials: true,
+      });
+
+      makeRequestAndExpectOne('/test-auth', 'foo', {
+        withCredentials: true,
+      });
+    });
+
     it('should cache POST with the differing body in string form', () => {
       makeRequestAndExpectOne('/test-1', null, {method: 'POST', transferCache: true, body: 'foo'});
       makeRequestAndExpectNone('/test-1', 'POST', {transferCache: true, body: 'foo'});
@@ -581,6 +592,16 @@ describe('TransferCache', () => {
         makeRequestAndExpectNone('/test-auth');
       });
 
+      it(`should not cache requests with credentials when 'includeRequestsWithAuthHeaders' is 'true'`, async () => {
+        makeRequestAndExpectOne('/test-auth', 'foo', {
+          withCredentials: true,
+        });
+
+        makeRequestAndExpectOne('/test-auth', 'foo', {
+          withCredentials: true,
+        });
+      });
+
       it('should cache a POST request', () => {
         makeRequestAndExpectOne('/include?foo=1', 'post-body', {method: 'POST'});