Description
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.
References8
- github.com/shd101wyy/crossnote/commit/e4890d64502e53b717cce0cb7…
- github.com/shd101wyy/crossnote/pull/443
- github.com/shd101wyy/crossnote/releases/tag/0.9.30
- github.com/shd101wyy/vscode-markdown-preview-enhanced/commit/0d…
- github.com/shd101wyy/vscode-markdown-preview-enhanced/pull/2320
- github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/…
- github.com/shd101wyy/vscode-markdown-preview-enhanced/security/…
- github.com/shd101wyy/vscode-markdown-preview-enhanced/security/…
Metrics
- CVSS 4.0
-
8.5
HIGH
Score source: CNA
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/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 - EPSS — exploit probability
- 0% percentile: 23 · as of 11 November 2026
- CWE
- CWE-94
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.