CVE-2026-118661

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.

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

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

• UNSCOREDCVE-2026-101287
• UNSCOREDCVE-2026-111749PoC
• CRITICALCVE-2026-112352
• CRITICALCVE-2026-76186PoC

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