{"id":"CVE-2026-54566","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-54566","generatedAt":"2026-10-28T01:47:32.349Z","title":"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…","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.","published":"2026-10-14T20:17:47.000Z","lastModified":"2026-10-16T16:00:34.000Z","status":"Awaiting Analysis","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"4.0","score":8.5,"severity":"HIGH","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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-94"],"affected":[],"epss":{"score":0.00296,"percentile":0.22075,"date":"2026-10-26","history":[{"date":"2026-10-15","score":0.00296,"percentile":0.20775}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.30%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-14T20:17:47.000Z","detail":{"score":"8.5","severity":"HIGH","publishedAt":"2026-10-14T20:17:47.403Z"},"summary":"New CVE, high severity (CVSS 8.5)."}],"references":[{"url":"https://github.com/shd101wyy/crossnote/commit/e4890d64502e53b717cce0cb73f1a78b244dc640","source":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/crossnote/pull/443","source":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/crossnote/releases/tag/0.9.30","source":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/commit/0d4010988c6ae56a38c6dec4a7509cbd5a7dcb4c","source":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/pull/2320","source":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/tag/0.8.29","source":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/security/advisories/GHSA-427h-jhpr-8jch","source":"security-advisories@github.com"},{"url":"https://github.com/shd101wyy/vscode-markdown-preview-enhanced/security/advisories/GHSA-427h-jhpr-8jch","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-54566","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}