# CVE-2026-71439 — mermaid-js mermaid

> As of 2026-08-07, CVE-2026-71439 is a Medium-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in mermaid-js mermaid, CVSS v4.0 5.3, EPSS 0.3% (31.8th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-71439 as of 2026-08-07; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-08-07

## What is CVE-2026-71439?

Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. From version 11.6.0 until 11.16.1, Mermaid Radar Diagrams allow arbitrary large values for the ticks parameter, which can cause high CPU usage and freeze the rendering webpage or JavaScript process for long periods of time, potentially until the process is killed from memory exhaustion. This issue is fixed in version 11.16.1.

The record classifies CVE-2026-71439 under weakness classes [CWE-606](https://cwe.mitre.org/data/definitions/606.html), [CWE-1322](https://cwe.mitre.org/data/definitions/1322.html). 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 60 days ago.

## Severity and exploitation probability

- **CVSS v4.0 base score:** 5.3 — Medium (derived from score) (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 31.8% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.9/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-08-06, last modified 2026-08-07

## Is CVE-2026-71439 being exploited?

It currently carries a trending score of 37 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **mermaid-js**: mermaid

Affected software packages:

- `npm:mermaid` — patched in 11.16.1

## How to fix CVE-2026-71439

Fixed versions are recorded for 1 package: npm:mermaid 11.16.1. No vendor patch reference has been recorded for CVE-2026-71439 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-71439

No threat campaign in the Threadlinqs corpus currently references CVE-2026-71439, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, GitHub Security Advisories, FIRST EPSS, NVD. Last verified by Threadlinqs on 2026-08-10. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com](https://github.com/mermaid-js/mermaid/security/advisories/GHSA-rhh3-jpg6-66xh)

**Other references**

- [github.com](https://github.com/mermaid-js/mermaid/pull/8022)
- [github.com (59b22fad2b3bb04f87a476c84a8a2b24679e607e)](https://github.com/mermaid-js/mermaid/commit/59b22fad2b3bb04f87a476c84a8a2b24679e607e)
- [github.com (mermaid%4011.16)](https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.16.1)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-71439
Full detection coverage and IOCs for threats exploiting CVE-2026-71439 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp