CVE-2026-71438
LowCVSS 2.4Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
Mermaid before 10.9.8 and 11.16.1 is vulnerable to prototype pollution via configuration setters when untrusted data is passed. Diagram-supplied config is not affected.
Risk Assessment
Risk of JavaScript object manipulation in applications that forward untrusted data to Mermaid configuration.
Recommendation
Upgrade Mermaid to 10.9.8 or 11.16.1 and avoid passing untrusted data to configuration.
Original NVD description (English source)
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.