Vulnerability Description
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>.
Related Weaknesses (CWE)
References
- https://github.com/mermaid-js/mermaid/commit/37ff937f1da2e19f882fd1db01235db4d01
- https://github.com/mermaid-js/mermaid/commit/4e2d512bf5bf6f9de1a8f0a48da78dc4d09
- https://github.com/mermaid-js/mermaid/security/advisories/GHSA-ghcm-xqfw-q4vr
- https://github.com/mermaid-js/mermaid/security/advisories/GHSA-ghcm-xqfw-q4vr
FAQ
What is CVE-2026-41149?
CVE-2026-41149 is a documented vulnerability. 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 i...
How severe is CVE-2026-41149?
CVSS scoring is not yet available for CVE-2026-41149. Check NVD for updates.
Is there a patch for CVE-2026-41149?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.