CVE-2026-71437: Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts

Routine

MEDIUM 6.5

CVE-2026-71437 is a medium-severity flaw (CVSS 6.5) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. From version 11.5.0 until 11.16.1, Mermaid Architecture Diagrams are vulnerable to prototype pollution when a diagram defines a group with an id of __proto__. Because the group id is used directly as an object property key without validation, an attacker who can supply diagram text can pollute Object.prototype, potentially affecting the behavio

Why this priority

CISA SSVC: public proof of concept

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-1321
Published	2026-08-06
Last modified	2026-10-24

Publisher (CNA): GitHub, Inc.

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-08-06 22:18 UTCPublished CVE record published
2026-10-24 15:10 UTCUpdated Record last modified

Exact fixes by distribution

npm · mermaid · FIXED · 11.16.1 · vulnerable: >= 11.5.0, < 11.16.1 · source

npm install mermaid@">=11.16.1" npm ls mermaid

Fedora 46 · sugar-calculator · FIXED · 47-14.fc46 · FEDORA-2026-38eeb9e279 · source

sudo dnf upgrade --advisory=FEDORA-2026-38eeb9e279

Fedora ELN · selinux-policy · FIXED · 45.23-1.eln159 · FEDORA-2026-3668c969a2 · source

sudo dnf upgrade --advisory=FEDORA-2026-3668c969a2

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-71437?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-71437 being exploited?

CVE-2026-71437 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-71437 affect?

CVE-2026-71437 affects affected software. Severity is medium (CVSS 6.5). Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. From version 11.5.0 until 11.16.1, Mermaid Architecture Diagrams are vulnerable to prototype pollution when a diagram defines a group wi

How urgent is CVE-2026-71437?

Priority 36/100. CISA SSVC: public proof of concept

References

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