---
id: CVE-2026-116802
title: DOMPurify before 3.4.17 XSS via SMIL attributeName Guard Bypass in XHTML Mode
summary: >-
  DOMPurify before 3.4.17 contains a cross-site scripting vulnerability that
  allows attackers to bypass the SMIL attributeName=href guard when
  PARSER_MEDIA_TYPE is application/xhtml+xml, because transformCaseFunc does not
  lowercase attribu…
severity: medium
cvss: 6.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'
cvssSource: cna
cwe:
  - CWE-79
vendor: cure53
product: DOMPurify
affected:
  - DOMPurify < 3.4.17
published: '2026-10-26'
updated: '2026-10-26'
sourceUpdated: '2026-10-26T23:05:34.457Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-116802'
references:
  - url: >-
      https://github.com/cure53/DOMPurify/security/advisories/GHSA-c6gr-qvv4-5v3f
    label: GitHub Security Advisory (GHSA-c6gr-qvv4-5v3f)
  - url: >-
      https://www.vulncheck.com/advisories/dompurify-before-3.4.17-xss-via-smil-attributename-guard-bypass-in-xhtml-mode
    label: >-
      VulnCheck Advisory: DOMPurify before 3.4.17 XSS via SMIL attributeName
      Guard Bypass in XHTML Mode
tags:
  - cve.org
epss: 0.00217
epssPercentile: 0.12072
ingestedAt: '2026-10-27T16:11:59.139Z'
---

## Overview

DOMPurify before 3.4.17 contains a cross-site scripting vulnerability that allows attackers to bypass the SMIL attributeName=href guard when PARSER_MEDIA_TYPE is application/xhtml+xml, because transformCaseFunc does not lowercase attribute names. Attackers can submit SVG with an animate or set element using attributeName="href" and a javascript: entry in values to execute script when users click the sanitized link.

## Affected

- `DOMPurify < 3.4.17`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.