CVE-2026-34226 PUBLISHED

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Versions prior to 20.8.9 may attach cookies from the current page origin (window.location) instead of the request target URL when fetch(..., { credentials: "include" }) is used. This can leak cookies from origin A to destination B. Version 20.8.9 fixes the issue.

• https://github.com/capricorn86/happy-dom/security/advisories/GHSA-w4gp-fjgq-3q4g
• https://github.com/capricorn86/happy-dom/pull/2117
• https://github.com/capricorn86/happy-dom/commit/68324c21d7b98f53f7bb5a7b3e185bda7106e751
• https://github.com/capricorn86/happy-dom/blob/f8d8cad41e9722fab9eefb9dfb3cca696462e908/packages/happy-dom/src/fetch/utilities/FetchRequestHeaderUtility.ts
• https://github.com/capricorn86/happy-dom/releases/tag/v20.8.9

• CWE-201: Insertion of Sensitive Information Into Sent Data CWE
• CWE-359: Exposure of Private Personal Information to an Unauthorized Actor CWE