{"id":"CVE-2026-71437","revision":null,"records":[{"revision":"e3f446184a4a4b6d911ce4e46b2a7d6d","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-71437","aliases":[],"title":"Mermaid Architecture diagrams are vulnerable to prototype pollution","description":"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.","state":0,"publishedAt":"2026-08-06T19:51:52.975+00:00","modifiedAt":"2026-08-07T17:37:35.933+00:00","affected":[{"ecosystem":"Vendor product","name":"mermaid","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"mermaid-js\",\n                    \"product\": \"mermaid\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 11.5.0, < 11.16.1\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"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","score":6.5,"severity":"MEDIUM"}],"references":["https://github.com/mermaid-js/mermaid/security/advisories/GHSA-3rrr-jr9j-h3q3","https://github.com/mermaid-js/mermaid/pull/8022","https://github.com/mermaid-js/mermaid/commit/99af3fc35ef0a9a9c8c6314521344d67523ddccf","https://github.com/mermaid-js/mermaid/releases/tag/mermaid@11.16.1"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-71437","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-71437","identifiers":["CVE-2026-71437"]},"retained":false,"historicalAffected":[]},{"revision":"9209fd67aef64aa2ae277d300d17485b","observedAt":"2026-11-07T14:23:22.018+00:00","statement":{"source":"euvd","id":"EUVD-2026-54242","aliases":["CVE-2026-71437","GHSA-3rrr-jr9j-h3q3"],"title":"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…","description":"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. 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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.","state":0,"publishedAt":"2026-08-06T22:18:30.713+00:00","modifiedAt":"2026-10-24T15:10:00.19+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · security-advisories@github.com · Secondary","vector":"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/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","score":6.5,"severity":"MEDIUM"}],"references":["https://github.com/mermaid-js/mermaid/commit/99af3fc35ef0a9a9c8c6314521344d67523ddccf","https://github.com/mermaid-js/mermaid/pull/8022","https://github.com/mermaid-js/mermaid/releases/tag/mermaid@11.16.1","https://github.com/mermaid-js/mermaid/security/advisories/GHSA-3rrr-jr9j-h3q3"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-71437","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Awaiting Analysis","weaknesses":["CWE-1321"],"productCriteria":[],"sourceDates":{"published":"2026-08-06T22:18:30.713","lastModified":"2026-10-24T15:10:00.190"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-71437","identifiers":["CVE-2026-71437"]},"retained":false,"historicalAffected":[]},{"revision":"3db83e0d887043d5a9f208c6f10a3237","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-3rrr-jr9j-h3q3","aliases":["CVE-2026-71437"],"title":"Mermaid Architecture diagrams are vulnerable to prototype pollution","description":"Rendering an untrusted `architecture-beta` diagram lets the diagram author write an arbitrary property with the value `horizontal` or `vertical` onto `Object.prototype`. A group id of `__proto__` is accepted as a valid parent.\n\n### Impact\n\nAny code in the same realm that reads a property of that name from an arbitrary object, or enumerates an object with bare `for...in`, observes the injected value (which can only be the string `horizontal` or `vertical`.\n\nThis may mean corrupted option/config defaults, bypassed truthiness checks, causing denial of service or logic corruption in the embedding application.\n\nBecause the injected value cannot be an object or function, this is not directly exploitable for remote code execution.\n\n### PoC\n\n```\narchitecture-beta\n      group mermaidPrototypePollutionMarker(cloud)[Marker]\n      service a(server)[A] in __proto__\n      service b(server)[B] in mermaidPrototypePollutionMarker\n      a:R -- L:b\n```\n\nThe vulnerable write was introduced in commit [cb0a4703bdf01d47508bde1c08aa9a980d70bc20](https://github.com/mermaid-js/mermaid/commit/cb0a4703bdf01d47508bde1c08aa9a980d70bc20) and first shipped in `mermaid@11.5.0`. The lines are unchanged in every release since.\n\n### Patches\n\nThis has been patched by https://github.com/mermaid-js/mermaid/commit/99af3fc35ef0a9a9c8c6314521344d67523ddccf, released in [Mermaid v11.16.1](https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.16.1)\n\n### Workarounds\n\nThere are no known workarounds. Please update to a patched version.\n\n### References\n\n_Are there any links users can visit to find out more?_\n\n- https://github.com/mermaid-js/mermaid/commit/99af3fc35ef0a9a9c8c6314521344d67523ddccf\n- https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.16.1","state":0,"publishedAt":"2026-08-06T19:51:59+00:00","modifiedAt":"2026-09-10T03:51:12.9600837+00:00","affected":[{"ecosystem":"npm","name":"mermaid","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"11.5.0"},{"kind":"fixed","version":"11.16.1"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"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","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/mermaid-js/mermaid/security/advisories/GHSA-3rrr-jr9j-h3q3","https://github.com/mermaid-js/mermaid/pull/8022","https://github.com/mermaid-js/mermaid/commit/99af3fc35ef0a9a9c8c6314521344d67523ddccf","https://github.com/mermaid-js/mermaid","https://github.com/mermaid-js/mermaid/releases/tag/mermaid@11.16.1"],"sourceUrl":"https://github.com/advisories/GHSA-3rrr-jr9j-h3q3","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-3rrr-jr9j-h3q3","identifiers":["GHSA-3rrr-jr9j-h3q3","CVE-2026-71437"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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