Markdown Preview Enhanced: Remote Code Execution via VM Sandbox Escape in `.crossnote/config.js` and `.crossnote/parser.js`
Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.29, Markdown Preview Enhanced evaluates repository-controlled .crossnote/config.js and .crossnote/parser.js files with vm.runInNewContext, which does not provide a security boundary from the Node.js host realm. Opening a Markdown file in a malicious repository automatically loads these files, and prototype-chain traversal can reach the host Function constructor and process object, allowing operating-system commands to execute as the victim account without further interaction. Both configuration evaluation and parser-hook evaluation are affected, and the attack does not depend on module-scoped require being available. This issue is fixed in version 0.8.29.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-54566
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 16:07 UTC · Revision 1
Source evidence
Markdown Preview Enhanced: Remote Code Execution via VM Sandbox Escape in `.crossnote/config.js` and `.crossnote/parser.js`
core-osv · Original sourcePublished 14 Oct 2026, 19:08 UTC
Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.29, Markdown Preview Enhanced evaluates repository-controlled .crossnote/config.js and .crossnote/parser.js files with vm.runInNewContext, which does not provide a security boundary from the Node.js host realm. Opening a Markdown file in a malicious repository automatically loads these files, and prototype-chain traversal can reach the host Function constructor and process object, allowing operating-system commands to execute as the victim account without further interaction. Both configuration evaluation and parser-hook evaluation are affected, and the attack does not depend on module-scoped require being available. This issue is fixed in version 0.8.29.
osv:CVE-2026-54566
Complete source record
{
"id": "8c6ca0266e38d4eb7eee6f86cc258103a51bcb39b052b115d56b1b623ad8cec6",
"url": "https://osv.dev/vulnerability/CVE-2026-54566",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Markdown Preview Enhanced: Remote Code Execution via VM Sandbox Escape in `.crossnote/config.js` and `.crossnote/parser.js`",
"summary": "Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.29, Markdown Preview Enhanced evaluates repository-controlled .crossnote/config.js and .crossnote/parser.js files with vm.runInNewContext, which does not provide a security boundary from the Node.js host realm. Opening a Markdown file in a malicious repository automatically loads these files, and prototype-chain traversal can reach the host Function constructor and process object, allowing operating-system commands to execute as the victim account without further interaction. Both configuration evaluation and parser-hook evaluation are affected, and the attack does not depend on module-scoped require being available. This issue is fixed in version 0.8.29.",
"evidence": "osv:CVE-2026-54566",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2026-54566",
"aliases": [
"CVE-2026-54566",
"GHSA-427h-jhpr-8jch"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/shd101wyy/crossnote",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "e4890d64502e53b717cce0cb73f1a78b244dc640"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"fixed": "e4890d64502e53b717cce0cb73f1a78b244dc640"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "e4890d64502e53b717cce0cb73f1a78b244dc640"
}
],
"source": "REFERENCES_TAG",
"original_tag": "0.9.30"
}
]
}
},
{
"repo": "https://github.com/shd101wyy/vscode-markdown-preview-enhanced",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "0d4010988c6ae56a38c6dec4a7509cbd5a7dcb4c"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "0.8.29"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "0d4010988c6ae56a38c6dec4a7509cbd5a7dcb4c"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "0d4010988c6ae56a38c6dec4a7509cbd5a7dcb4c"
}
],
"source": "REFERENCES_TAG",
"original_tag": "0.8.29"
},
{
"range": [
{
"introduced": "0"
},
{
"fixed": "0.8.29"
}
],
"source": "DESCRIPTION"
}
]
}
}
],
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],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-54566.json"
}
}
],
"modified": "2026-10-28T02:30:37.193866659Z",
"provider": "osv",
"references": [
"https://github.com/shd101wyy/crossnote/releases/tag/0.9.30",
"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/tag/0.8.29",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54566.json",
"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/security/advisories/GHSA-427h-jhpr-8jch",
"https://nvd.nist.gov/vuln/detail/CVE-2026-54566",
"https://github.com/shd101wyy/crossnote/commit/e4890d64502e53b717cce0cb73f1a78b244dc640",
"https://github.com/shd101wyy/crossnote/pull/443",
"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/commit/0d4010988c6ae56a38c6dec4a7509cbd5a7dcb4c",
"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/pull/2320"
],
"provider_metadata": {
"cwe_ids": [
"CWE-94"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54566.json"
}
},
"related_cves": [
{
"value": "CVE-2026-54566",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 504493,
"published_at": "2026-10-14T19:08:43.663+00:00"
}