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CVE-2026-34226

7.5 · HIGH

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface.

Published Mar 27, 2026CWE-201EPSS 0.59%

Overview

CVE-2026-34226 is a high-severity vulnerability. It was published on March 27, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/capricorn86/happy-dom/blob/f8d8cad41e9722fab9eefb9dfb3cca696462e908/packages/happy-dom/src/fetch/utilities/FetchRequestHeaderUtility.tsGitHubgithub.com/capricorn86/happy-dom/commit/68324c21d7b98f53f7bb5a7b3e185bda7106e751GitHubgithub.com/capricorn86/happy-dom/pull/2117GitHubgithub.com/capricorn86/happy-dom/releases/tag/v20.8.9GitHubgithub.com/capricorn86/happy-dom/security/advisories/GHSA-w4gp-fjgq-3q4gRefaccess.redhat.com/security/cve/CVE-2026-34226Refbugzilla.redhat.com/show_bug.cgi?id=2452519Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34226.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-34226?

CVE-2026-34226 is a high-severity vulnerability. It was published on March 27, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-34226?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-34226?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-34226?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-34226 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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