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CVE-2026-71438GHSA-C4C3-PG64-4M4V

Mermaid configuration APIs allow prototype pollution

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 10.9.8, 11.16.1
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • mermaid-js mermaid

    fixed in 10.9.8; From 11.0.0-alpha.1 · fixed in 11.16.1

  • mermaidnpm

    From 11.0.0-alpha.1 · fixed in 11.16.1

  • mermaidnpm

    fixed in 10.9.8

References 6

GitHub · mermaid-js/mermaid