CVE-2026-50159

Name	CVE-2026-50159
Description	Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.8 and 11.16.1, Mermaid is vulnerable to CSS injection via sibling combinator selectors generated from diagram-supplied class or id names. An attacker who can supply diagram text can inject arbitrary CSS into the rendered page, potentially altering the appearance or behavior of unrelated page elements. This issue is fixed in versions 10.9.8 and 11.16.1.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
node-mermaid (PTS)	bullseye	8.7.0+ds+~cs27.17.17-3+deb11u2	vulnerable
	forky	9.2.2+~2.0.0-1	vulnerable
	sid	9.2.2+~2.0.0-2	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
node-mermaid	source	(unstable)	(unfixed)

Notes

https://github.com/mermaid-js/mermaid/security/advisories/GHSA-6x64-9x62-f2gx
Fixed by: https://github.com/mermaid-js/mermaid/commit/12d472c9ed43f94814b110da8d7a9ae6dd5266ed (mermaid@11.16.1)
Fixed by: https://github.com/mermaid-js/mermaid/commit/7e83f1533318b307764d961906a73377266f4c5e (v10.9.7)