CVE-2026-65902

DOMPurify before 3.4.7 Hook Mutation Pollution via allowedTags

MEDIUM
6.1
CVSS Score
Published: July 23, 2026 at 01:16 PM UTC
Updated: October 24, 2026 at 01:10 PM UTC
1 product affected across 1 vendorDOMPurify

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Severity
MEDIUM6.1
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

DOMPurify before 3.4.7 (affected versions <= 3.4.5) 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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.4.7
Vendor states this is fixed in 3.4.7 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.1MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-501

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