CVE-2026-118661

MEDIUM 6.5

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

CVSS Score

6.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-565
Vendor	capricorn86
Product	happy-dom
Published	Oct 28, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Affected Versions

capricorn86 / happy-dom

< 20.14.6

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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