GHSA-62vg-58rm-qff7 - @angular/router: Denial of Service via Unmatched Empty-Path Outlet Route Matching in Server-Side Rendering (SSR)

A denial of service (DoS) vulnerability was identified in `@angular/router` when Server-Side Rendering (SSR) is enabled on Node.js (V8). During route recognition, `@angular/router` fails to validate whether an auxiliary outlet segment in the URL matches a route configured for that specific outlet name. Because unconfigured empty-path outlet groups (such as `a:/()`, `x:/(...)`, or `///(...)`) are not rejected during matching, the router repeatedly re-evaluates the route configuration against each arbitrary outlet segment provided in the URL. When a request URL contains multiple arbitrary empty-path outlet segments, this improper matching forces the router to instantiate duplicate `ActivatedRouteSnapshot` trees, repeatedly execute `canMatch` guards and route resolvers, and allocate separate copies of route parameters and `queryParams` for each unconfigured outlet. An unauthenticated remote attacker can exploit this behavior by sending requests with crafted outlet segments to exhaust the Node.js memory heap or overwhelm CPU resources, leading to SSR worker termination and service disruption. ### Impact Successful exploitation allows an unauthenticated remote attacker to exhaust the Node.js heap with a single crafted request or a small number of concurrent requests, terminating the SSR worker process with a fatal JavaScript heap out-of-memory crash. When the matched routes declare `canMatch` guards or resolvers, a single short request can also trigger repeated guard or resolver executions, increasing load on backend services and holding worker connections open. * **Transient Allocation:** Memory is released once route recognition completes; there is no persistent memory leak. The primary impact is process termination. * **Client-side SPAs Unaffected:** Client-side Angular applications running in the browser are not vulnerable, as browser memory consumption does not cross a security boundary. * **Prerendering (SSG) Unaffected:** Build-time prerendering does not pro