Medium 5.3Published May 22, 2026

CVE-2026-41149Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection

Updated under an hour ago (Oct 27, 2026, 3:23 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for mermaid-js mermaid

Exploited in the last 30 days

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>.

CVSS: 5.3 MEDIUM (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L
Weakness (CWE): CWE-94
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: May 22, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

mermaid-js mermaid mermaid_js:mermaid (from the name)	from 11.0.0-alpha.1, < 11.15.0; before 10.9.6	CNA record

References

References

https://github.com/mermaid-js/mermaid/security/advisories/GHSA-ghcm-xqfw-q4vr	x-refsource-confirm
https://github.com/mermaid-js/mermaid/commit/37ff937f1da2e19f882fd1db01235db4d01f4056	x-refsource-misc
https://github.com/mermaid-js/mermaid/commit/4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.