GHSA-45q2-gjvg-7973: Angular: SSRF via protocol-relative and backslash URLs in Angular Platform-Server

A Server-Side Request Forgery (SSRF) vulnerability exists in @angular/platform-server due to improper handling of URLs during Server-Side Rendering (SSR).

When an attacker sends a request such as GET /\evil.com/ HTTP/1.1 the server engine (Express, etc.) passes the URL string to Angular’s rendering functions.

Because the URL parser normalizes the backslash to a forward slash for HTTP/HTTPS schemes, the internal state of the application is hijacked to believe the current origin is evil.com. This misinterpretation tricks the application into treating the attacker’s domain as the local origin. Consequently, any relative HttpClient requests or PlatformLocation.hostname references are redirected to the attacker controlled server, potentially exposing internal APIs or metadata services.

Affected APIs:

• renderModule
• renderApplication
• CommonEngine (from @angular/ssr)

Non-Affected APIs:

• AngularAppEngine (from @angular/ssr)
• AngularNodeAppEngine (from @angular/ssr)