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CVE-2026-41159

5.3 · MEDIUM

Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts.

Published May 29, 2026CWE-94EPSS 0.55%

Overview

CVE-2026-41159 is a medium-severity vulnerability. It was published on May 29, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.6 and 11.15.0, Mermaid's default configuration allows injecting CSS that applies outside of the Mermaid diagram via the fontFamily, themeCSS, and altFontFamily configuration options. The injected CSS exploits stylis's & (scope reference) handling. :not(&) escapes the #mermaid-xxx automatic scoping, applying styles to all page elements. Global at-rules (@font-face, @keyframes, @counter-style) are also injectable as stylis hoists them to top level. This allows page defacement and DOM attribute exfiltration via CSS :has() selectors. This vulnerability is fixed in 10.9.6 and 11.15.0.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aaGitHubgithub.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76GitHubgithub.com/mermaid-js/mermaid/releases/tag/[email protected]GitHubgithub.com/mermaid-js/mermaid/releases/tag/v10.9.6GitHubgithub.com/mermaid-js/mermaid/security/advisories/GHSA-87f9-hvmw-gh4p

How CyberStrike helps

Frequently asked questions

What is CVE-2026-41159?

CVE-2026-41159 is a medium-severity vulnerability. It was published on May 29, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-41159?

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-41159?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-41159?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-41159 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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