CVE-2026-71437: medium-severity vulnerability in mermaid-js mermaid
Mermaid Architecture diagrams are vulnerable to prototype pollution
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.5epss 0.5%
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 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 behavior of the embedding application. This issue is fixed in version 11.16.1.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:H/SI:H/SA:H
Affected products
mermaid-js · mermaidRelated CVEs — mermaid-js mermaid
In the same product, most dangerous first.
CVE-2021-43861HIGHIncorrect sanitisation function leads to `XSS`EPSS 0.9%CVE-2022-31108MEDIUMArbitrary `CSS` injection into the generated graph affecting the container HTML in mermaid.jsEPSS 0.9%CVE-2025-54881MEDIUMMermaid improperly sanitizes of sequence diagram labels leading to XSSEPSS 0.8%CVE-2026-50159MEDIUMMermaid allows CSS injection applying to sibling elements of the diagramEPSS 0.6%CVE-2026-71436MEDIUMMermaid XY Charts are vulnerable to an infinite loop DoSEPSS 0.6%CVE-2026-71439MEDIUMMermaid radar diagrams are vulnerable to DoSEPSS 0.5%