Angular: Denial of Service via RouterLink Query Parameter Retention in Server-Side Rendering (SSR)

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. From 21.2.0 until 21.2.25 and 22.2.1, RouterLink directives rendered during Node.js server-side rendering retain computed UrlTree instances for the lifetime of each request. When queryParamsHandling is set to merge or preserve, either per link or through defaultQueryParamsHandling, every rendered link can retain a copy of attacker-controlled query parameters in its UrlTree. When upstream proxies or load balancers forward oversized query strings without rejecting them at the edge, multiple affected links and overlapping renders can amplify heap use until the Node.js old-space heap is exhausted and the SSR worker terminates. Numeric query-parameter names increase allocation pressure but are not required, memory is released after rendering completes, and pure client-side SPAs are not affected. This issue is fixed in versions 21.2.25 and 22.2.1.