{"id":"CVE-2026-100721","aliases":["GHSA-5h3f-q97h-ccvc"],"url":"https://o3.security/vulnerability/CVE-2026-100721","summary":"vm2 before 3.12.2 Authorization Bypass via Custom Resolver","details":"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-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.","published":"2026-09-27T01:28:28.596Z","modified":"2026-09-28T03:48:31.532515631Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":{"url":"https://github.com/patriksimek/vm2/commit/6ac3916da84e060c403e407b6b6318fcc66b0e72","label":"patriksimek/vm2@6ac3916"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100721.json"},{"type":"ADVISORY","url":"https://github.com/patriksimek/vm2/security/advisories/GHSA-5h3f-q97h-ccvc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100721"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/vm2-before-3.12.2-authorization-bypass-via-custom-resolver"},{"type":"FIX","url":"https://github.com/patriksimek/vm2/commit/6ac3916da84e060c403e407b6b6318fcc66b0e72"},{"type":"FIX","url":"https://github.com/patriksimek/vm2/commit/91034466bfb7f56b95fd48083ec6ca36d058f164"},{"type":"FIX","url":"https://github.com/patriksimek/vm2/commit/ab4ee7d803e8c80155e9eb3672226bddbca4aa9c"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-28T03:48:31.532515631Z"}}