Description

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.

Quick Facts

References

• https://github.com/patriksimek/vm2/commit/6ac3916da84e060c40…
• https://github.com/patriksimek/vm2/commit/91034466bfb7f56b95…
• https://github.com/patriksimek/vm2/commit/ab4ee7d803e8c80155…
• https://github.com/patriksimek/vm2/security/advisories/GHSA-…
• https://www.vulncheck.com/advisories/vm2-before-3.12.2-autho…

External Resources