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.
References6
- github.com/mermaid-js/mermaid/commit/12d472c9ed43f94814b110da8d…
- github.com/mermaid-js/mermaid/commit/7e83f1533318b307764d961906…
- github.com/mermaid-js/mermaid/pull/8022
- github.com/mermaid-js/mermaid/releases/tag/[email protected]
- github.com/mermaid-js/mermaid/releases/tag/v10.9.8
- github.com/mermaid-js/mermaid/security/advisories/GHSA-6x64-9x6…
Metrics
- CVSS 4.0
-
5.3
MEDIUM
Score source: 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 49 · as of 12 November 2026
- CWE
- CWE-94
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.