Vulnerability · Published Jul 23, 2026 · Assigned by VulnCheck

CVE-2026-65902DOMPurify before 3.4.7 Hook Mutation Pollution via allowedTags

Medium 6.1

In plain English

A medium-severity security flaw in DOMPurify from cure53. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.1Medium

Exploit odds (30 days)0.4%top 70.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

DOMPurify before 3.4.7 passes direct references to the module-level DEFAULT_ALLOWED_TAGS and DEFAULT_ALLOWED_ATTR sets to the uponSanitizeElement and uponSanitizeAttribute hooks via data.allowedTags / data.allowedAttributes when sanitize is called without an explicit cfg.ALLOWED_TAGS / cfg.ALLOWED_ATTR array. A hook that mutates these fields permanently widens the default allow-lists for the lifetime of the DOMPurify instance, so all subsequent default-config sanitize calls inherit the widened defaults and attacker payloads using the poisoned tag/attribute name survive sanitization. removeAllHooks(), clearConfig(), and passing a fresh cfg do not recover the state; only constructing a new DOMPurify instance does.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	node-dompurify	no fix listed	DEBIAN-CVE-2026-65902
Debian:13	node-dompurify	no fix listed	DEBIAN-CVE-2026-65902
Debian:14	node-dompurify	3.4.12+dfsg-1	DEBIAN-CVE-2026-65902
Ubuntu:22.04:LTS	node-dompurify	no fix listed	UBUNTU-CVE-2026-65902
Ubuntu:24.04:LTS	node-dompurify	no fix listed	UBUNTU-CVE-2026-65902
Ubuntu:26.04:LTS	node-dompurify	no fix listed	UBUNTU-CVE-2026-65902
npm	dompurify	3.4.7	GHSA-76mc-f452-cxcm

Affected products (as reported)

Vendor	Product	Versions
cure53	DOMPurify	0 – before 3.4.7

Weakness: CWE-501 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

GitHub Security Advisory (GHSA-76mc-f452-cxcm) vendor-advisory
Patch Commit patch
VulnCheck Advisory: DOMPurify before 3.4.7 Hook Mutation Pollution via allowedTags third-party-advisory