Medium
Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection
Type: advisorySources: OSV
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,
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-41149
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 7 Nov 2026, 04:00 UTC · Revision 1
Source evidence
Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection
core-osv · Original sourcePublished 22 May 2026, 22:34 UTC
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,
osv:CVE-2026-41149
Complete source record
{
"id": "78658e21964ede383679652fb91259ce11e47fb948223987d2fce19cf14ba567",
"url": "https://osv.dev/vulnerability/CVE-2026-41149",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injection",
"summary": "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,",
"evidence": "osv:CVE-2026-41149",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2026-41149",
"aliases": [
"CVE-2026-41149",
"GHSA-ghcm-xqfw-q4vr"
],
"metrics": [
{
"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"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/mermaid-js/mermaid",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "41646dfd43ac83f001b03c70605feb036afae46d"
},
{
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},
{
"fixed": "37ff937f1da2e19f882fd1db01235db4d01f4056"
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{
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}
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"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
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},
{
"fixed": "10.9.6"
}
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"strategy": "StringRangeExpression"
},
{
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"source": "REFERENCES_COMMIT"
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{
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"source": "REFERENCES_COMMIT"
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}
}
],
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"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-41149.json"
}
}
],
"modified": "2026-10-28T02:30:49.509162608Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41149.json",
"https://github.com/mermaid-js/mermaid/security/advisories/GHSA-ghcm-xqfw-q4vr",
"https://nvd.nist.gov/vuln/detail/CVE-2026-41149",
"https://github.com/mermaid-js/mermaid/commit/37ff937f1da2e19f882fd1db01235db4d01f4056",
"https://github.com/mermaid-js/mermaid/commit/4e2d512bf5bf6f9de1a8f0a48da78dc4d09ac4f3"
],
"provider_metadata": {
"cwe_ids": [
"CWE-94"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41149.json"
}
},
"related_cves": [
{
"value": "CVE-2026-41149",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 517955,
"published_at": "2026-05-22T22:34:36.944+00:00"
}