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Fencer Vulns
medium 6.5

CVE-2026-118661 json

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

published 2026-10-28 11 d ago modified 2026-11-03 5 d ago also GHSA-5fpq-26gf-qwcr , EUVD-2026-112468

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 19%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm happy-dom 20.14.6

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-118661 updated cvss 6.5

happy-dom: happy-dom: Cookie injection via improper cookie domain validation

  • Red Hat Ansible Automation Platform 2 automation-platform-ui 2.6.15-1.el9ap, automation-gateway 2.5.20260923-1.el9ap, ansible-automation-platform-26/gateway-rhel9, ansible-automation-platform-27/gateway-rhel9
    affected: no fix available, no fix planned “Out of support scope”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-feature-server-rhel9
    affected: no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
5 d ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 19% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/capricorn86/happy-dom/security/advisories/GHSA-5fpq-26gf-qwcr referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm happy-dom
<20.14.6
20.14.6

Affected products

  • capricorn86 happy-dom

Classification

Weakness
  • CWE-565 Reliance on Cookies without Validation and Integrity Checking

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.