CVE-2026-50159
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.
Does this matter?
Lower severity and a low EPSS score (0.61%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 4.0
- 5.3 MEDIUMCVSS: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/M
- EPSS
- 0.61% probability · 47th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-94
- Source
- security-advisories@github.com
References
- https://github.com/mermaid-js/mermaid/commit/12d472c9ed43f94814b110da8d7a9ae6dd5266ed
- https://github.com/mermaid-js/mermaid/commit/7e83f1533318b307764d961906a73377266f4c5e
- https://github.com/mermaid-js/mermaid/pull/8022
- https://github.com/mermaid-js/mermaid/releases/tag/mermaid@11.16.1
- https://github.com/mermaid-js/mermaid/releases/tag/v10.9.8
- https://github.com/mermaid-js/mermaid/security/advisories/GHSA-6x64-9x62-f2gx
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.