CVE-2026-71439 mermaid-js CVE debrief

Who should care

Defenders of systems using Mermaid Radar Diagrams should assess exposure and verify if Mermaid version is 11.16.1 or later. This includes operators, platform administrators, vulnerability management teams, and security teams. They should review the official advisory to validate affected scope, severity, and vendor guidance. Defenders should also monitor for potential high CPU usage and freezing issues.

Why it matters

CVE-2026-71439 allows for high CPU usage and potential freezing of Mermaid Radar Diagrams, requiring defenders to assess exposure and verify Mermaid version.

• Potential high CPU usage and freezing of the rendering webpage or JavaScript process
• Need to verify Mermaid version and assess exposure

Technical summary

Mermaid Radar Diagrams allow arbitrary large values for the ticks parameter, potentially causing high CPU usage and freezing of the rendering webpage or JavaScript process. This issue is fixed in version 11.16.1. The vulnerability has a CVSS score of 5.3 and a severity of MEDIUM. Defenders should assess exposure and verify Mermaid version. The CVE record and NVD entry provide details on the vulnerability, and defenders should review the official advisory to validate affected scope, severity, and vendor guidance. The vulnerability affects Mermaid Radar Diagrams, which are used to create and modify diagrams and charts.

Defensive priority

Assess exposure in systems using Mermaid Radar Diagrams

Recommended defensive actions

• Assess exposure in systems using Mermaid Radar Diagrams
• Verify if Mermaid version is 11.16.1 or later
• Monitor for potential high CPU usage and freezing issues
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the Mermaid Radar Diagrams vulnerability, allowing for high CPU usage and potential freezing of the rendering webpage or JavaScript process. The vulnerability has a CVSS score of 5.3 and a severity of MEDIUM. The issue is fixed in version 11.16.1. Defenders should verify Mermaid version and assess exposure. The CVE Program and NVD records are the primary sources for this information.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.