Angular Service Worker Policy-Bypass & Credential-Stripping Vulnerabilities

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 22.0.0-rc.2, 21.2.15 20.3.22, and 19.2.23, 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. This vulnerability is fixed in 22.0.0-rc.2, 21.2.15, 20.3.22, and 19.2.23.