CVE-2026-41149
CVE-2026-41149 is a medium-severity vulnerability with a CVSS 4.0 base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-94.
Key facts
- Severity: Medium (CVSS 4.0 base score 5.3)
- EPSS exploit prediction: 0% (32nd percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-31520
- Weakness: CWE-94
- Published:
- Last modified:
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>.
Frequently asked questions
- What is CVE-2026-41149?
- 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>.
- How severe is CVE-2026-41149?
- CVE-2026-41149 has a CVSS 4.0 base score of 5.3, rated medium severity.
- Is CVE-2026-41149 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-41149?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-41149 have an EU (EUVD) identifier?
- Yes. CVE-2026-41149 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31520.
- When was CVE-2026-41149 published?
- CVE-2026-41149 was published on 2026-05-22 and last updated on 2026-06-17.
References
- https://github.com/mermaid-js/mermaid/commit/37ff937f1da2e19f882fd1db01235db4d01f4056
- https://github.com/mermaid-js/mermaid/commit/4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3
- https://github.com/mermaid-js/mermaid/security/advisories/GHSA-ghcm-xqfw-q4vr
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