Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection_CVE-2026-41149

{
    "lastseen": "",
    "description": "Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Versions 10.9.5 and earlier, as well as 11.0.0-alpha.1 through 11.14.0, are vulnerable to HTML injection under the default configuration. Specifically, the classDef directive in Mermaid state diagrams permits DOM injection that escapes the SVG context. However, <script> tags are stripped, which prevents cross-site scripting (XSS). This issue has been fixed in versions 10.9.6 and 11.15.0. If developers are unable to immediately upgrade, they can work around this issue by setting \"securityLevel\": \"sandbox\", which prevents the issue by rendering the mermaid diagram in a sandboxed <iframe>.",
    "published": "2026-05-22T22:34:36.944Z",
    "modified": "2026-05-22T22:34:37.412Z",
    "type": "cve",
    "title": "Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection",
    "source": "GitHub_M",
    "references": "https://github.com/mermaid-js/mermaid/security/advisories/GHSA-ghcm-xqfw-q4vr\nhttps://github.com/mermaid-js/mermaid/commit/37ff937f1da2e19f882fd1db01235db4d01f4056\nhttps://github.com/mermaid-js/mermaid/commit/4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3",
    "id": "CVE-2026-41149",
    "bulletinFamily": "",
    "cwe": [
        "CWE-94"
    ],
    "cvelist": null,
    "sourceData": "mermaid-js mermaid >= 11.0.0-alpha.1, < 11.15.0\nmermaid-js mermaid < 10.9.6",
    "sourceHref": "",
    "cvss": {
        "score": 5.3,
        "severity": "MEDIUM",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
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            "privilegesRequired": "",
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "mermaid",
    "version": ">= 11.0.0-alpha.1, < 11.15.0",
    "vendor": "mermaid-js",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
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    "ai_score": 0
}