Summary
Mermaid XY Charts are vulnerable to an infinite loop DoS
Proof-of-concept
xychart
x-axis 1 --> 1
line [1, 2]
Workarounds
There are no known workarounds. Please update to the latest version or apply the patch.
References
Impact
Mermaid XY Charts are vulnerable to an infinite loop DoS attack in the setXAxisRangeData(), when configuring an X-Axis with invalid parameters.
As each loop appends an element to an array, this would generally only cause an RangeError: Invalid array length to appear after a few seconds, but may cause the page/JavaScript process to crash due to memory exhaustion, depending on the environment.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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This has been patched in https://github.com/mermaid-js/mermaid/commit/630aa7e5dd417e1f56bff2a1ce8df2c5ad08d289 and released in Mermaid v11.16.1.
A backport has been made for the v10 branch in ef60adc837d9d5107af21285f01e83dea309bd0a and was released in Mermaid v10.9.8
Frequently Asked Questions
- What is CVE-2026-71436? CVE-2026-71436 is a medium-severity security vulnerability in mermaid (npm), affecting versions >= 10.6.0, < 10.9.8. It is fixed in 10.9.8, 11.16.1.
- Which versions of mermaid are affected by CVE-2026-71436? mermaid (npm) versions >= 10.6.0, < 10.9.8 is affected.
- Is there a fix for CVE-2026-71436? Yes. CVE-2026-71436 is fixed in 10.9.8, 11.16.1. Upgrade to this version or later.
- Is CVE-2026-71436 exploitable, and should I be worried? Whether CVE-2026-71436 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-71436 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-71436?
- Upgrade
mermaidto 10.9.8 or later - Upgrade
mermaidto 11.16.1 or later
- Upgrade