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Vulnerabilities

Vulnerability · CVE-2026-34226

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

Published Mar 27, 2026 · catalog updated Aug 19, 2026 · happy dom

Check if you run it

No confirmed exploitation is on record for CVE-2026-34226. EPSS is 0.59%. Act only if a listed version of happy dom is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.59%
Remediation
Advisory link
Affected products
cpe capricorn86/happy dom

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 ( ) instead of the request target URL when is used. This can leak cookies from origin A to destination B. Version 20.8.9 fixes the issue.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe capricorn86/happy domversion unspecified

How to fix CVE-2026-34226

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-34226. EPSS is 0.59%. Act only if a listed version of happy dom is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-201; CWE-359. EPSS 0.59%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 27, 2026 · NIST NVD

    Detected

    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 ( ) instead of the request target URL when is used. This can leak cookies from origin A to destination B. Version 20.8.9 fixes the issue.

  2. Aug 19, 2026 · NIST NVD

    Updated

    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 ( ) instead of the request target URL when is used. This can leak cookies from origin A to destination B. Version 20.8.9 fixes the issue.

Sources

  • CVE.orgVulnerability recordCVE-2026-34226

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-34226

    30-day exploitation probability 0.6%

    first.org
  • NIST NVDVulnerability recordCVE-2026-34226

    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 ( ) instead of the request target URL when is used. Th

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.