CVE-2026-71438Mermaid configuration APIs allow prototype pollution
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 2.4 LOW (v4.0, CNA)CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:A/VC:N/VI:L/VA:L/SC:H/SI:H/SA:H
- Weakness (CWE)
- CWE-1321
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Awaiting Analysis
- Record last updated
- Aug 7, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
mermaid-js mermaid mermaid_js:mermaid (from the name) | before 10.9.8; from 11.0.0-alpha.1, < 11.16.1 | CNA record |
References
- https://github.com/mermaid-js/mermaid/security/advisories/GHSA-c4c3-pg64-4m4vx-refsource-confirm
- https://github.com/mermaid-js/mermaid/pull/8022x-refsource-misc
- https://github.com/mermaid-js/mermaid/commit/2cd6dcf735533b323507e3e889ffdea870540b43x-refsource-misc
- https://github.com/mermaid-js/mermaid/commit/c34b07a0815842327e70794d69b0c8c5a1e2a956x-refsource-misc
- https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.16.1x-refsource-misc
- https://github.com/mermaid-js/mermaid/releases/tag/v10.9.8x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.