What’s Vulnerable › Vulnerabilities

CVE-2026-49978: DOMPurify IN_PLACE Sanitization Bypass via Attached Shadow Root Inside <template>.content

• 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: 2026-07-14 · updated 2026-10-24
• Weakness: CWE-79

Description

DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Prior to 3.4.7, DOMPurify IN_PLACE sanitization could skip shadow contents attached to an element inside <template>.content, allowing attacker-controlled markup such as event handlers, JavaScript URLs, or scripts to survive and execute when an application cloned and inserted the sanitized template. This issue is fixed in version 3.4.7.

Affected products

• cure53 DOMPurify: before 3.4.7 — fixed in 3.4.7

How to fix

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

References

• https://github.com/cure53/DOMPurify/commit/ca30f070c360df162a3e3848e80e6fd3c9e74bff
• https://github.com/cure53/DOMPurify/releases/tag/3.4.7
• https://github.com/cure53/DOMPurify/security/advisories/GHSA-rp9w-3fw7-7cwq
• https://github.com/cure53/DOMPurify/security/advisories/GHSA-rp9w-3fw7-7cwq

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