Vulnerability · Published Oct 14, 2026 · Assigned by GitHub_M

CVE-2026-54566Markdown Preview Enhanced: Remote Code Execution via VM Sandbox Escape in `.crossnote/config.js` and `.crossnote/parser.js`

High 8.5

In plain English

A high-severity code injection in vscode-markdown-preview-enhanced from shd101wyy. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities).

Severity (CVSS 4.0)8.5High

Exploit odds (30 days)0.3%top 77.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
shd101wyy	vscode-markdown-preview-enhanced	< 0.8.29

Weakness: CWE-94 · Vector: 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

References

https://github.com/shd101wyy/vscode-markdown-preview-enhanced/security/advisories/GHSA-427h-jhpr-8jch x_refsource_CONFIRM
https://github.com/shd101wyy/crossnote/pull/443 x_refsource_MISC
https://github.com/shd101wyy/vscode-markdown-preview-enhanced/pull/2320 x_refsource_MISC
https://github.com/shd101wyy/crossnote/commit/e4890d64502e53b717cce0cb73f1a78b244dc640 x_refsource_MISC
https://github.com/shd101wyy/vscode-markdown-preview-enhanced/commit/0d4010988c6ae56a38c6dec4a7509cbd5a7dcb4c x_refsource_MISC
https://github.com/shd101wyy/crossnote/releases/tag/0.9.30 x_refsource_MISC
https://github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/tag/0.8.29 x_refsource_MISC