CVE-2026-100721
published 2026-09-27CVE-2026-100721: vm2 before 3.12.2 contains an authorization bypass in the NodeVM external-module resolver. When an embedder configures `require.external` with a custom…
PriorityP260critical9CVSS 3.1
AVNACHPRNUINSCCHIHAH
EPSS
0.40%
32.0th percentile
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.
Affected
2 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| patriksimek | vm2 | < 3.12.2 | 3.12.2 |
| vm2_project | vm2 | >= 0 < 3.12.2 | 3.12.2 |
CVSS provenance
nvdv3.19.0CRITICALCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
nvdv4.09.5CRITICALCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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GHSA
vm2: NodeVM custom resolution bypasses external path boundaries
ghsa·2026-10-05
CVE-2026-100721 [CRITICAL] CWE-863 vm2: NodeVM custom resolution bypasses external path boundaries
vm2: NodeVM custom resolution bypasses external path boundaries
## Summary
At source revision `91034466bfb7f56b95fd48083ec6ca36d058f164` of vm2 3.11.8, an untrusted `NodeVM` guest can turn one allowlisted custom-resolved module into authorization for a separate file whose path merely shares the resolved path's string prefix. `LegacyResolver.customResolve` stores the resolved path in `this.externals` as `^` without an end or separator boundary; a later absolute require of a sibling such as `foo2/index.js` therefore passes the external check and is loaded through `hostRequire` when the configured context is `host`. The decisive attack loaded `foo` as `FOO_OK` and then executed the prefix-sharing sibling, which returned `PREFIX_PWN` after invoking `child_process`; an otherwise identical con
GHSA
vm2 before 3.12.2 contains an authorization bypass in the NodeVM external-module resolver.
ghsa_unreviewed·2026-09-27
CVE-2026-100721 [CRITICAL] CWE-863 vm2 before 3.12.2 contains an authorization bypass in the NodeVM external-module resolver.
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 wrappe
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
https://github.com/patriksimek/vm2/commit/6ac3916da84e060c403e407b6b6318fcc66b0e72https://github.com/patriksimek/vm2/commit/91034466bfb7f56b95fd48083ec6ca36d058f164https://github.com/patriksimek/vm2/commit/ab4ee7d803e8c80155e9eb3672226bddbca4aa9chttps://github.com/patriksimek/vm2/security/advisories/GHSA-5h3f-q97h-ccvchttps://www.vulncheck.com/advisories/vm2-before-3.12.2-authorization-bypass-via-custom-resolver
2026-09-27
Published