Angular HTTP Client Has XSRF Token Leakage via Protocol-Relative URLs

Vulnerability Description

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to versions 19.2.16, 20.3.14, and 21.0.1, there is a XSRF token leakage via protocol-relative URLs in angular HTTP clients. The vulnerability is a Credential Leak by App Logic that leads to the unauthorized disclosure of the Cross-Site Request Forgery (XSRF) token to an attacker-controlled domain. Angular's HttpClient has a built-in XSRF protection mechanism that works by checking if a request URL starts with a protocol (http:// or https://) to determine if it is cross-origin. If the URL starts with protocol-relative URL (//), it is incorrectly treated as a same-origin request, and the XSRF token is automatically added to the X-XSRF-TOKEN header. This issue has been patched in versions 19.2.16, 20.3.14, and 21.0.1. A workaround for this issue involves avoiding using protocol-relative URLs (URLs starting with //) in HttpClient requests. All backend communication URLs should be hardcoded as relative paths (starting with a single /) or fully qualified, trusted absolute URLs.

References

• https://github.com/angular/angular/security/advisories/GHSA-58c5-g7wp-6w37
• https://github.com/angular/angular/commit/0276479e7d0e280e0f8d26fa567d3b7aa97a516f
• https://github.com/angular/angular/commit/05fe6686a97fa0bcd3cf157805b3612033f975bc
• https://github.com/angular/angular/commit/3240d856d942727372a705252f7c8c115394a41e
• https://github.com/angular/angular/releases/tag/19.2.16
• https://github.com/angular/angular/releases/tag/20.3.14
• https://github.com/angular/angular/releases/tag/21.0.1