CVE-2026-71438
Reported by GitHub_M · Published August 6, 2026
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.
Risk Scores
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| mermaid-js | mermaid | < 10.9.8, >= 11.0.0-alpha.1, < 11.16.1 |
| mermaid-js | mermaid | >= 11.0.0-alpha.1, < 11.16.1, < 10.9.8 |
| chainguard | gitlab-rails-ce-fips-18.9 | 0 |
| chainguard | gitlab-rails-ce-fips-19.2 | 0 |
| wolfi | langfuse-3 | 0, 0 |
| chainguard | langfuse-fips-2 | 0 |
| npm | mermaid | 11.0.0-alpha.1, 0 |
| mermaid-js | mermaid | |
| chainguard | langfuse-4 | 0 |
| chainguard | langfuse-fips-3 | 0 |
| chainguard | langfuse-3 | 0, 0 |
| chainguard | gitlab-rails-ce-19.2 | 0 |
| chainguard | jupyter-base-notebook | 0 |
| chainguard | commercial-gitlab-rails-ee-19.1 | 0 |
| chainguard | gitlab-rails-ce-fips-19.1 | 0 |
| chainguard | langfuse-fips-4 | 0 |
| chainguard | gitlab-rails-ce-fips-19.0 | 0 |
| chainguard | gitlab-rails-ce-fips-18.11 | 0 |
| wolfi | jupyter-base-notebook | 0 |
| chainguard | gitlab-rails-ce-fips-19.3 | 0 |
…and 4 more
Timeline
- Aug 6, 2026 CVE Published
- Aug 7, 2026 EPSS Score
- Aug 7, 2026 Coalition ESS Score
- Aug 9, 2026 Security Advisory
- Aug 24, 2026 EPSS Score
- Sep 6, 2026 EPSS Score
- Sep 15, 2026 EPSS Score
- Sep 18, 2026 EPSS Score
- Sep 24, 2026 EPSS Score
- Sep 26, 2026 EPSS Score
- Sep 30, 2026 EPSS Score
- Oct 2, 2026 EPSS Score
References
- https://github.com/mermaid-js/mermaid/security/advisories/GHSA-c4c3-pg64-4m4v x_refsource_CONFIRM
- https://github.com/mermaid-js/mermaid/pull/8022 x_refsource_MISC
- https://github.com/mermaid-js/mermaid/commit/2cd6dcf735533b323507e3e889ffdea870540b43 x_refsource_MISC
- https://github.com/mermaid-js/mermaid/commit/c34b07a0815842327e70794d69b0c8c5a1e2a956 x_refsource_MISC
- https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.16.1 x_refsource_MISC
- https://github.com/mermaid-js/mermaid/releases/tag/v10.9.8 x_refsource_MISC
- https://nvd.nist.gov/vuln/detail/CVE-2026-71438 advisory
- https://github.com/advisories/GHSA-c4c3-pg64-4m4v advisory