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

Summary

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.

Timeline

1. Nov 26, 2025, 10:18 PM UTCCVE published
2. Nov 28, 2025, 6:28 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Jun 2, 2026, 1:00 PM UTCRecord last updated

Affected versions

• angular angular

  From 21.0.0-next.0 · fixed in 21.0.1; From 20.0.0-next.0 · fixed in 20.3.14; fixed in 19.2.16

• @angular/commonnpm

  From 21.0.0-next.0 · fixed in 21.0.1

• @angular/commonnpm

  From 20.0.0-next.0 · fixed in 20.3.14

• @angular/commonnpm

  fixed in 19.2.16

References 7