CVE-2026-71438

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's configuration setters (mermaid.initialize, mermaidAPI.setConfig, and mermaidAPI.updateSiteConfig) merge caller-supplied configuration into Mermaid's internal config using the assignWithDepth deep-merge helper, which is vulnerable to prototype pollution. This is only exploitable if an application forwards untrusted data directly into one of these configuration entry points, which is outside their documented usage; diagram-supplied configuration (e.g. %%{init: {}}%% or YAML frontmatter) is not affected. This issue is fixed in versions 10.9.8 and 11.16.1.

References

https://github.com/mermaid-js/mermaid/security/advisories/GHSA-c4c3-pg64-4m4v

https://github.com/mermaid-js/mermaid/releases/tag/v10.9.8

https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.16.1

https://github.com/mermaid-js/mermaid/pull/8022

https://github.com/mermaid-js/mermaid/commit/c34b07a0815842327e70794d69b0c8c5a1e2a956

https://github.com/mermaid-js/mermaid/commit/2cd6dcf735533b323507e3e889ffdea870540b43

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4