{"id":"CVE-2026-54566","title":"Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code","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, whi…","severity":"high","cvss":8.5,"cvssVector":"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","cwe":["CWE-94"],"vendor":"shd101wyy","product":"vscode-markdown-preview-enhanced","affected":["vscode-markdown-preview-enhanced < 0.8.29"],"published":"2026-10-14","updated":"2026-10-16","sourceUpdated":"2026-10-16T16:00:33.533","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-54566","references":[{"url":"https://github.com/shd101wyy/crossnote/commit/e4890d64502e53b717cce0cb73f1a78b244dc640","label":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/crossnote/pull/443","label":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/crossnote/releases/tag/0.9.30","label":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/commit/0d4010988c6ae56a38c6dec4a7509cbd5a7dcb4c","label":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/pull/2320","label":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/tag/0.8.29","label":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/security/advisories/GHSA-427h-jhpr-8jch","label":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/security/advisories/GHSA-427h-jhpr-8jch","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd","cve.org","exploit-available"],"epss":0.00296,"epssPercentile":0.22135,"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"total","timestamp":"2026-10-14T19:44:50.050593Z"},"cvssSource":"cna","ingestedAt":"2026-10-14T20:53:12.376Z","slug":"CVE-2026-54566","body":"## Overview\n\nMarkdown 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":59,"depthScoreParts":{"impact":46.8,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":221899,"id":"CVE-2026-54566","ts":1792035898527,"field":"exploit_available","old":"false","new":"true"},{"seq":221898,"id":"CVE-2026-54566","ts":1792035898527,"field":"cvss","old":null,"new":"8.5"},{"seq":221897,"id":"CVE-2026-54566","ts":1792035898527,"field":"severity","old":"none","new":"high"}]}