CVE-2026-118661

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

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.

Affected

capricorn86 · happy-dom

CVSS v3.1 GITHUB

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

EPSS

0.27% chance of exploitation in the next 30 days, 20th percentile

Published

2026-10-28

Proof-of-concept exploits (1)

• advisories/GHSA-5fpq-26gf-qwcrfind archive

CVE references

• capricorn86/happy-dom/commit/f21dbd7d0a0c63cdd41954ba5d0f05def4e0f2b3REFERENCE
• capricorn86/happy-dom/pull/2477REFERENCE
• capricorn86/happy-dom/releases/tag/v20.14.6REFERENCE
• capricorn86/happy-dom/security/advisories/GHSA-5fpq-26gf-qwcrREFERENCE

References

• CVE Record
• NVD entry