CVE-2026-34226

Happy DOM's fetch credentials include uses page-origin cookies instead of target-origin cookies

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.

Affected

capricorn86 · happy-dom

CVSS v3.1 CNA

7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

0.59% chance of exploitation in the next 30 days, 47th percentile

Published

2026-03-27

Updated

2026-07-15

Proof-of-concept exploits (1)

• advisories/GHSA-w4gp-fjgq-3q4g

Security advisories

• capricorn86/happy-dom/security/advisories/GHSA-w4gp-fjgq-3q4g
• capricorn86/happy-dom/pull/2117

References

• CVE Record
• NVD entry