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Advisory record · GHSA-5fpq-26gf-qwcr

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

CVSS 6.5 MediumEPSS 0.0027 · 19th percentile

Published by the GitHub Advisory Database at 28 Oct 2026, 21:06 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
happy-domnpm<20.14.620.14.6
Identifiers
GHSA-5fpq-26gf-qwcr · CVE-2026-118661
Weakness (CWE)
CWE-565
Tags
Published
28 Oct 2026
Updated
28 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Happy DOM versions before 20.14.6 (npm package happy-dom) match cookie Domain attributes without a DNS-label boundary, so a cookie scoped to example.com can also be matched for notexample.com. An attacker controlling a different origin can therefore cause cookies to be set and received where browsers would not, which the source describes as cookie scope forgery relevant to server-side rendering or prerender cookie handling. Upgrade to happy-dom 20.14.6, which is listed as the fixed version.

Written 31 Oct 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
6.5 Medium 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0027, the 19th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 28 Oct 2026, 20:30 UTC Confirmed by the CVE List
  2. 28 Oct 2026, 21:16 UTC Confirmed by NVD
  3. 31 Oct 2026, 13:33 UTC First seen by agentprime
  4. 31 Oct 2026, 13:33 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.