vm2 before 3.11.7 Module Allowlist Bypass via Prefix Matching

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

vm2 before 3.11.7 contains a module allowlist bypass vulnerability in isPathAllowedForModule that uses raw string prefix matching instead of boundary-anchored comparison. Attackers can reach non-allowlisted packages sharing a prefix with allowlisted modules by performing relative requires from allowlisted packages when transitive loading is disabled.

Source published

17 Sep 2026 13:46:06 UTC

Source modified

17 Sep 2026 14:25:31 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 2.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS 3.1 · 4.2 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

vm2 before 3.11.7 contains a module allowlist bypass vulnerability in isPathAllowedForModule that uses raw string prefix matching instead of boundary-anchored comparison. Attackers can reach non-allowlisted packages sharing a prefix with allowlisted modules by performing relative requires from allowlisted packages when transitive loading is disabled.

Source published

Sep 17, 2026, 1:46:06 PM (timezone not stated)

Source modified

Sep 17, 2026, 2:25:31 PM (timezone not stated)

Observed here

11 Nov 2026 17:05:12 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 4.0 · 2.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

vm2 before 3.11.7 contains a module allowlist bypass vulnerability in isPathAllowedForModule that uses raw string prefix matching instead of boundary-anchored comparison. Attackers can reach non-allowlisted packages sharing a prefix with allowlisted modules by performing relative requires from allowlisted packages when transitive loading is disabled.

Source published

17 Sep 2026 14:17:59 UTC

Source modified

17 Sep 2026 15:17:00 UTC

Observed here

25 Oct 2026 16:19:22 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 2.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/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

CVSS 3.1 · [email protected] · Secondary · 4.2 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

## Summary `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. ## Where it is `lib/resolver-compat.js`, lines 122 to 132, quoted from HEAD `7a1f5100b96f48d34e0fe104ab37c0acc5944f92`: ```js isPathAllowedForModule(path, mod) { if (!super.isPathAllowed(path)) return false; if (mod) { if (mod.allowTransitive) return true; if (path.startsWith(mod.path)) { const rem = path.slice(mod.path.length); if (!/(?:^|[\\/])node_modules(?:$|[\\/])/.test(rem)) return true; } } return this.externals.some(regex => regex.test(path)); } ``` With `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. The `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. ## Impact Code 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. Two 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. ## Reachability `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. ## Suggested fix Require a separator after the prefix, so a sibling cannot match: ```js if (path === mod.path || path.startsWith(mod.path + path.sep)) { ``` That is the same anchoring the `rem` regex already applies to `node_modules`, applied one level earlier.

Source published

1 Oct 2026 15:26:45 UTC

Source modified

1 Oct 2026 15:45:05 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

Publisher rating · MODERATE

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-7q3f-wx44-378m. This link is maintained to preserve external references. ## Original Description vm2 before 3.11.7 contains a module allowlist bypass vulnerability in isPathAllowedForModule that uses raw string prefix matching instead of boundary-anchored comparison. Attackers can reach non-allowlisted packages sharing a prefix with allowlisted modules by performing relative requires from allowlisted packages when transitive loading is disabled.

Source published

17 Sep 2026 15:32:15 UTC

Source modified

1 Oct 2026 15:30:05 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

CVSS_V4 · CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/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

Publisher rating · LOW