{"id":"CVE-2026-100721","title":"vm2 before 3.12.2 contains an authorization bypass in the NodeVM external-module resolver","summary":"vm2 before 3.12.2 contains an authorization bypass in the NodeVM external-module resolver. When an embedder configures `require.external` with a custom resolver (and `context: 'host'`), `LegacyResolver.customResolve` in lib/resolver-comp…","severity":"critical","cvss":9,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H","cwe":["CWE-863"],"vendor":"patriksimek","product":"vm2","affected":["vm2 < 3.12.2"],"published":"2026-09-27","updated":"2026-09-27","sourceUpdated":"2026-09-27T02:17:18.070","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-100721","references":[{"url":"https://github.com/patriksimek/vm2/commit/6ac3916da84e060c403e407b6b6318fcc66b0e72","label":"disclosure@vulncheck.com"},{"url":"https://github.com/patriksimek/vm2/commit/91034466bfb7f56b95fd48083ec6ca36d058f164","label":"disclosure@vulncheck.com"},{"url":"https://github.com/patriksimek/vm2/commit/ab4ee7d803e8c80155e9eb3672226bddbca4aa9c","label":"disclosure@vulncheck.com"},{"url":"https://github.com/patriksimek/vm2/security/advisories/GHSA-5h3f-q97h-ccvc","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/vm2-before-3.12.2-authorization-bypass-via-custom-resolver","label":"disclosure@vulncheck.com"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-27T02:41:45.564Z","slug":"CVE-2026-100721","body":"## Overview\n\nvm2 before 3.12.2 contains an authorization bypass in the NodeVM external-module resolver. When an embedder configures `require.external` with a custom resolver (and `context: 'host'`), `LegacyResolver.customResolve` in lib/resolver-compat.js records the resolved module directory in `this.externals` as `new RegExp('^' + escapeRegExp(resolvedPath))`, without requiring a path separator or end-of-string boundary. Untrusted guest code can therefore require the allowlisted module (e.g. `foo`) and then require the absolute path of a non-allowlisted sibling whose path merely shares the resolved prefix (e.g. `.../node_modules/foo2/index.js`); the sibling passes `isPathAllowedForModule` and is loaded through `hostRequire`, so its top-level code runs in the host process before the exports are wrapped with `vm.readonly`, resulting in a sandbox escape and arbitrary code execution in the host context.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":50,"depthScoreParts":{"impact":49.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}