GHSA-c8p4-j97h-3vg8: happy-dom (CVE-2026-118660)

Package	Ecosystem	Affected	Fixed in
happy-dom	npm	<21.0.0	21.0.0

Machine-written summary

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

happy-dom versions before 21.0.0 make real server-side HTTP requests to arbitrary URLs when parsing HTML with iframe or stylesheet link elements, because these loads are enabled by default. An attacker who can supply HTML that the application parses on the server can trigger server-side request forgery, which may reach internal services and expose their responses. Upgrade happy-dom to version 21.0.0 or later.

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

Score	Rating	CVSS	Vector	Source
8.6	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0040, the 34th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 13:33 UTC First seen by agentprime
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.