High severity · published Mar 27, 2026
CVE-2026-34226
Happy DOM's fetch credentials include uses page-origin cookies instead of target-origin cookies
7.5
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 40% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HA
happy-dom · capricorn86
< 20.8.9 · source: vendor
HD
Happy Dom · Capricorn86
before 20.8.9 · source: NVD
RH
Red Hat Ansible Automation Platform 2 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34226
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-34226
Patch
https://github.com/capricorn86/happy-dom/blob/f8d8cad41e9722fab9eefb9dfb3cca696462e908/packages/happy-dom/src/fetch/utilities/FetchRequestHeaderUtility.ts
Patch
https://github.com/capricorn86/happy-dom/commit/68324c21d7b98f53f7bb5a7b3e185bda7106e751
Issue Tracking
https://github.com/capricorn86/happy-dom/pull/2117
Product
https://github.com/capricorn86/happy-dom/releases/tag/v20.8.9
Exploit
https://github.com/capricorn86/happy-dom/security/advisories/GHSA-w4gp-fjgq-3q4g
access.redhat.com
https://access.redhat.com/security/cve/CVE-2026-34226
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