---
id: CVE-2026-41149
title: >-
  Mermaid is a JavaScript tool that uses Markdown-inspired text to create and
  modify diagrams and charts
summary: >-
  Mermaid is a JavaScript tool that uses Markdown-inspired text to create and
  modify diagrams and charts. Versions 10.9.5 and earlier, as well as
  11.0.0-alpha.1 through 11.14.0, are vulnerable to HTML injection under the
  default configurat…
severity: none
cwe:
  - CWE-94
published: '2026-05-22'
updated: '2026-07-23'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-41149'
references:
  - url: >-
      https://github.com/mermaid-js/mermaid/commit/37ff937f1da2e19f882fd1db01235db4d01f4056
    label: security-advisories@github.com
  - url: >-
      https://github.com/mermaid-js/mermaid/commit/4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3
    label: security-advisories@github.com
  - url: >-
      https://github.com/mermaid-js/mermaid/security/advisories/GHSA-ghcm-xqfw-q4vr
    label: security-advisories@github.com
  - url: >-
      https://github.com/mermaid-js/mermaid/security/advisories/GHSA-ghcm-xqfw-q4vr
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00521
epssPercentile: 0.41689
ingestedAt: '2026-07-23T11:17:34.737Z'
---

## Overview

Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Versions 10.9.5 and earlier, as well as 11.0.0-alpha.1 through 11.14.0, are vulnerable to HTML injection under the default configuration. Specifically, the classDef directive in Mermaid state diagrams permits DOM injection that escapes the SVG context. However, <script> tags are stripped, which prevents cross-site scripting (XSS). This issue has been fixed in versions 10.9.6 and 11.15.0. If developers are unable to immediately upgrade, they can work around this issue by setting "securityLevel": "sandbox", which prevents the issue by rendering the mermaid diagram in a sandboxed <iframe>.

## Remediation

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