GHSA-gv2q-mqqv-365m Angular Service Worker Policy-Bypass & Credential-Stripping Vulnerabilities

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

An issue in the `@angular/service-worker` package compromises the integrity of request-policy enforcement during request reconstruction. When the Angular Service Worker intercepts network requests for matched assets, it reconstructs a new `Request` object using an internal helper function. During this reconstruction process, the helper function strips the strict, client-defined request redirect policy configuration (such as `redirect: 'error'`), falling back to the browser's default `'follow'` strategy. If the target web application makes client-side requests with a strict policy (e.g., expecting a network error instead of automatically following redirects), the service worker will bypass this instruction and automatically follow HTTP 3xx redirects to other destinations. This acts as an unintended proxy/intermediary ("Confused Deputy") and can result in cookie/credential exposure or same-origin session-restricted data leakage if public dynamic routes redirect to sensitive routes. Impact Web applications registering the `@angular/service-worker` package are vulnerable to this redirect-policy bypass if they make safe client-side fetch calls (such as `{ redirect: 'error' }`) to paths matched by a service worker asset group (such as lazy-loaded JavaScript bundles or dynamic public assets) that can return HTTP redirects to authenticated same-origin secure endpoints. By stripping developer-defined safety boundaries, the service worker allows the browser to transparently query and return data from credentials-guarded resources that should have been blocked at the network barrier. Attack Preconditions To successfully exploit this vulnerability, all of the following application states and parameters must concurrently exist: 1. Active Angular Service Worker: The target application uses `@angular/service-worker` and has an active registration of `ngsw-worker.js` inside the client's browser context. 2. Asset Group Matching: An `assetGroups` pattern in `ngsw-config.json` encompasses the target dynamic routing endpoint. 3. Same-Origin Dynamic Redirection: The server routes a public matched asset route to a service that returns an HTTP 3xx redirect pointing to a sensitive, session-restricted same-origin private route (e.g., `/private/account-summary.json`). 4. Established User Session: The victim user currently has an active authentication state, such as valid same-origin session cookies or auth headers stored by the browser. 5. Client-Side Safe Fetch Call: The application initiates an explicit fetch request to the route with safety parameters: `{ redirect: 'error' }`. Mitigations & Workarounds If upgrading the `@angular/service-worker` package is not immediately feasible, developers should implement the following defensive measures: • Avoid Public-to-Private Dynamic Redirection: Refactor the server architecture so that public paths matched by service worker asset groups never issue HTTP 3xx redirects to authenticated same-origin secure endpoints. • Strict Cookie Configuration: Apply strict flags to session cookies (`SameSite=Strict; Secure; HttpOnly`) and consider explicit route isolations (such as subdomains) for credential-guarded private resources. • Exclude Secure Endpoints from SW Config: Verify your `ngsw-config.json` settings and ensure that patterns targeting dynamic, secure endpoints are explicitly excluded from automatic asset groups or caching scopes. Patches • 22.0.0-rc.2 • 21.2.15 • 20.3.22 • 19.2.23