An open redirect vulnerability was identified in "@angular/platform-server" when Server-Side Rendering (SSR) is enabled. When Angular SSR renders an incoming request, URL resolution and platform navigation are managed by "ServerPlatformLocation" using "resolveUrl" (or "parseUrl" in v20). While "resolveUrl" rejected protocol-relative URLs whose raw string directly started with "//", this check ran prior to WHATWG URL normalization. When a request URL includes a popping dot-segment followed by multiple slashes (such as "/.//evil.test" or serialized from router route shapes like "/.;/(//evil.test)"), the input bypassed the initial "urlStr.startsWith('//')" check. Subsequent WHATWG URL parsing resolved the dot-segments and resulted in a "pathname" starting with "//" ("//evil.test"). Consequently, "ServerPlatformLocation" stored "pathname = '//evil.test'". When "@angular/ssr" detected a mismatch between the rendered URL and the router's final location state, it emitted the unnormalized pathname into the HTTP "Location" response header, producing an HTTP 302 redirect with "Location: //evil.test", which browsers resolve as a protocol-relative navigation off-origin.