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CVE-2026-41238

DOMPurify: Prototype Pollution to XSS Bypass via CUSTOM_ELEMENT_HANDLING Fallback

Published: Apr 23, 2026Updated: Apr 23, 2026 Sources: CVE List
NVD MITRE
6.9CVSS
MEDIUM

DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Versions 3.0.1 through 3.3.3 are vulnerable to a prototype pollution-based XSS bypass. When an application uses `DOMPurify.sanitize()` with the default configuration (no `CUSTOM_ELEMENT_HANDLING` option), a prior prototype pollution gadget can inject permissive `tagNameCheck` and `attributeNameCheck` regex values into `Object.prototype`, causing DOMPurify to allow arbitrary custom elements with arbitrary attributes — including event handlers — through sanitization. Version 3.4.0 fixes the issue.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

CVSS Vector Breakdown

AV:NAC:HPR:NUI:RS:CC:HI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:LIntegrity
Low
A:NAvailability
None

Weaknesses

CWE-79CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')CWE-1321CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Affected Products

DOMPurify
cure53

Attack Graph

Products CVE Techniques Tactics

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Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

MITRE ATT&CK

2 techniques
Execution
Initial Access
View detailed technique mapping

References

https://github.com/cure53/DOMPurify/security/advisories/GHSA-v9jr-rg53-9pgp
github.com
https://github.com/cure53/DOMPurify/releases/tag/3.4.0
github.com

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