CVE-2026-34226

Name: CVE-2026-34226
Creator: NVD / NIST
Published: 2026-03-27T22:16:23.113+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.41%

Last modified Jun 17, 2026

CVE-2026-34226 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.41% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.41%

32.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Capricorn86	Happy Dom	< 20.8.9

References

https://github.com/capricorn86/happy-dom/blob/f8d8cad41e9722fab9eefb9dfb3cca696462e908/packages/happy-dom/src/fetch/utilities/FetchRequestHeaderUtility.tsPatch
https://github.com/capricorn86/happy-dom/commit/68324c21d7b98f53f7bb5a7b3e185bda7106e751Patch
https://github.com/capricorn86/happy-dom/pull/2117Issue Tracking, Patch
https://github.com/capricorn86/happy-dom/releases/tag/v20.8.9Product, Release Notes
https://github.com/capricorn86/happy-dom/security/advisories/GHSA-w4gp-fjgq-3q4gExploit, Vendor Advisory

Timeline

Published: Mar 27, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-34226?

How severe is CVE-2026-34226?

CVE-2026-34226 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.41% probability of exploitation in the next 30 days.

How do I fix CVE-2026-34226?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-34226?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST