Medium 5.3Published May 29, 2026

CVE-2026-41159Mermaid: Improper sanitization of configuration leads to CSS injection

Updated under an hour ago (Oct 28, 2026, 3:40 AM ET)

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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. 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 (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: Modified
Record last updated: Jul 1, 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
mermaid_project mermaid mermaid_project:mermaid	before 10.9.6; from 11.0.0 before 11.15.0	NVD

References

References

https://github.com/mermaid-js/mermaid/security/advisories/GHSA-87f9-hvmw-gh4p	x-refsource-confirm, third-party-advisory
https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aa	x-refsource-misc
https://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76	x-refsource-misc
https://github.com/mermaid-js/mermaid/releases/tag/mermaid@11.15.0	x-refsource-misc, release-notes
https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6	x-refsource-misc, release-notes

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.