{"id":"GHSA-7q3f-wx44-378m","summary":"vm2: External module allowlist uses a raw prefix test, so a prefix-sharing sibling package is treated as allowlisted","details":"## Summary\n\n`isPathAllowedForModule` decides whether a resolved path belongs to an allowlisted external module using a raw string prefix test. `node_modules/foo2` starts with `node_modules/foo`, so a package whose name merely shares a prefix with an allowlisted one is treated as being inside it, and a relative require from the allowlisted package reaches it even with transitive loading disabled.\n\n## Where it is\n\n`lib/resolver-compat.js`, lines 122 to 132, quoted from HEAD `7a1f5100b96f48d34e0fe104ab37c0acc5944f92`:\n\n```js\nisPathAllowedForModule(path, mod) {\n    if (!super.isPathAllowed(path)) return false;\n    if (mod) {\n        if (mod.allowTransitive) return true;\n        if (path.startsWith(mod.path)) {\n            const rem = path.slice(mod.path.length);\n            if (!/(?:^|[\\\\/])node_modules(?:$|[\\\\/])/.test(rem)) return true;\n        }\n    }\n    return this.externals.some(regex =\u003e regex.test(path));\n}\n```\n\nWith `mod.path` of `.../node_modules/foo` and a resolved path of `.../node_modules/foo2/index.js`, `startsWith` is true and `rem` is `2/index.js`, which contains no `node_modules` segment, so the function returns true.\n\nThe `node_modules` test in `rem` is what stops a genuine transitive dependency from slipping through. It does not stop a sibling, because a sibling's remainder never contains that segment.\n\n## Impact\n\nCode running in `NodeVM` under an external module allowlist with `transitive: false` can reach a package that was not allowlisted, provided an allowlisted package performs a relative require to a prefix-sharing sibling.\n\nTwo preconditions are worth stating plainly rather than leaving implicit. The deployment must already have such a package layout, and an allowlisted package must have a reachable code path that does the relative require. This is not something the attacker creates; it is something they find. That narrows it considerably, and it is why I have not scored it higher.\n\n## Reachability\n\n`NodeVM.run` at `lib/nodevm.js:506` executes the script. `require` comes from `createRequireForModule` at `lib/setup-node-sandbox.js:168-172` and reaches the resolver callback at `lib/nodevm.js:380-384`. `LegacyResolver.resolveFull` at `lib/resolver-compat.js:145-160` sets `currMod` for direct requires, the relative specifier resolves through `DefaultResolver.resolveFull` and `tryFile` at `lib/resolver.js:327-330`, and the authorization decision lands on the function above.\n\n## Suggested fix\n\nRequire a separator after the prefix, so a sibling cannot match:\n\n```js\nif (path === mod.path || path.startsWith(mod.path + path.sep)) {\n```\n\nThat is the same anchoring the `rem` regex already applies to `node_modules`, applied one level earlier.","aliases":["CVE-2026-92945"],"modified":"2026-10-01T15:45:05.655741416Z","published":"2026-10-01T15:26:45Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-10-01T15:26:45Z","nvd_published_at":null,"cwe_ids":["CWE-22","CWE-863"],"severity":"MODERATE"},"references":[{"type":"WEB","url":"https://github.com/patriksimek/vm2/security/advisories/GHSA-7q3f-wx44-378m"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-92945"},{"type":"WEB","url":"https://github.com/patriksimek/vm2/commit/6ac3916da84e060c403e407b6b6318fcc66b0e72"},{"type":"PACKAGE","url":"https://github.com/patriksimek/vm2"},{"type":"WEB","url":"https://github.com/patriksimek/vm2/releases/tag/v3.11.7"},{"type":"WEB","url":"https://www.vulncheck.com/advisories/vm2-before-3.11.7-module-allowlist-bypass-via-prefix-matching"}],"affected":[{"package":{"name":"vm2","ecosystem":"npm","purl":"pkg:npm/vm2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.11.7"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 3.11.6","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-7q3f-wx44-378m/GHSA-7q3f-wx44-378m.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N"}]}