What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-23 · updated 2026-10-29
• Weakness: CWE-501

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 products

• cure53 DOMPurify: before 3.4.7 — fixed in 3.4.7
• cure53 DOMPurify: before 3.4.7 — fixed in 3.4.7

How to fix

Upgrade to a fixed version: cure53 DOMPurify 3.4.7; cure53 DOMPurify 3.4.7. Check the vendor advisory for mitigations.

References

• https://github.com/cure53/DOMPurify/commit/7996f1dc78eb8b7922388aed75d94a9f8fad9a36
• https://github.com/cure53/DOMPurify/security/advisories/GHSA-76mc-f452-cxcm
• https://www.vulncheck.com/advisories/dompurify-before-hook-mutation-pollution-via-allowedtags
• https://github.com/cure53/DOMPurify/security/advisories/GHSA-76mc-f452-cxcm

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