Medium 6.5Published Oct 28, 2026

CVE-2026-118661Happy DOM: Cookie scope forgery: no DNS-label boundary on Domain= matching , attacker origin sets victim cookies

Updated under an hour ago (Oct 30, 2026, 6:10 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Prior to 20.14.6, Happy DOM's CookieContainer in src/cookie/CookieContainer.ts does not correctly validate or match Domain cookie attributes. It can accept a Domain unrelated to the origin setting the cookie, including a public suffix, and separately treats an unrelated suffix-sharing hostname as a match because cookieMatchesURL does not enforce a DNS-label boundary. In server-side rendering and prerendering applications that contact attacker-controlled origins and then make requests to a victim origin, these behaviors can plant and deliver a forged cookie, enabling cookie injection or session fixation. This issue is fixed in version 20.14.6.

CVSS: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness (CWE): CWE-565
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Oct 28, 2026
First seen by InfoSec Signals: Oct 28, 2026

Affected products

Affected products

capricorn86 happy-dom capricorn86:happy_dom (from the name)	before 20.14.6	CNA record

References

References

https://github.com/capricorn86/happy-dom/security/advisories/GHSA-5fpq-26gf-qwcr	x-refsource-confirm
https://github.com/capricorn86/happy-dom/pull/2477	x-refsource-misc
https://github.com/capricorn86/happy-dom/commit/f21dbd7d0a0c63cdd41954ba5d0f05def4e0f2b3	x-refsource-misc
https://github.com/capricorn86/happy-dom/releases/tag/v20.14.6	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.