CVE-2026-41159
CVE-2026-41159 · Mermaid: Improper sanitization of configuration leads to CSS injection
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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.
CVSS 5.3 · Medium · EPSS 0.5% · Fix available
- Published
- Updated
Affected products and versions
mermaid
- Versions
- >= 11.0.0-alpha.1, < 11.15.0: Affected
- < 10.9.6: Affected
No fix published
node-mermaid Debian:14
- Versions
- 8.11.0+ds+~cs29.13.22-1
- 8.13.2+ds+~cs30.13.21-1
- 8.13.2+ds+~cs30.13.21-1.1
- 8.13.3+ds+~cs26.13.21-1
- 8.13.3+ds+~cs26.13.21-2
- 8.13.8+~cs10.4.16-1
- 8.14.0+ds1+~cs11.4.14-1
- 8.14.0+~cs11.4.14-1
- 8.7.0+ds+~cs27.17.17-1
- 8.7.0+ds+~cs27.17.17-2
- 8.7.0+ds+~cs27.17.17-2~bpo10+1
- 8.7.0+ds+~cs27.17.17-3
- 8.9.1+ds+~cs26.20.25-1
- 8.9.3+ds+~cs29.13.19-1
- 9.2.2+~2.0.0-1
- 9.2.2+~2.0.0-2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
mermaid npm
- Affected ranges
- SEMVER: ≥ 11.0.0-alpha.1, < 11.15.0
Update to 11.15.0
mermaid npm
- Affected ranges
- SEMVER: < 10.9.6
Update to 10.9.6
node-mermaid Ubuntu:22.04:LTS
- Versions
- 8.7.0+ds+~cs27.17.17-3
- 8.13.3+ds+~cs26.13.21-1
- 8.13.3+ds+~cs26.13.21-2
- 8.13.8+~cs10.4.16-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
node-mermaid Ubuntu:26.10
- Versions
- 9.2.2+~2.0.0-1
- 9.2.2+~2.0.0-2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
Original sources
- https://github.com/mermaid-js/mermaid/security/advisories/GHSA-87f9-hvmw-gh4p
- https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aa
- https://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76
- https://github.com/mermaid-js/mermaid/releases/tag/[email protected]
- https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6
- https://nvd.nist.gov/vuln/detail/CVE-2026-41159