CVE-2026-71438

2.4 LOW 0.4% exploit odds Fix listed Other

What it is

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.

At a glance

Exploitability: Can be exploited locally on the machine with an admin-level account, but needs a user to act. Limited direct impact.
Exploit odds: 0.4% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-08-06 22:18 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-24 15:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.4% in the next 30 days (EPSS).
Severity: 2.4 LOW (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-08-06 22:18 UTC
Last modified: 2026-10-24 15:10 UTC
Exploit probability: 0.4% · EPSS, next 30 days
Weakness: CWE-1321 · Prototype pollution
Record status: Awaiting Analysis

Attack profile CVSS 4.0 · 2.4

Attack vector: Local
Complexity: Low
Attack requirements: Present
Privileges needed: High
User interaction: Active
Confidentiality: None
Integrity: Low
Availability: Low

Raw vector

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-71438.md and follow it. Check whether this project is affected by CVE-2026-71438. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record