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Dossier · Vulnerability

Vulnerability · NVD published 2026-09-27

CVE-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 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.

  1. Disclosed
  2. 1 day →First PoC

Signals

Exploited in the wild
Not on KEVNot in CISA's catalogue as of the last daily pull. Absence is not proof of safety.
EPSS · 30-day forecast
0%Chance of exploitation in the next 30 days, 33th percentile of all CVEs. A forecast; KEV outranks it.
CVSS · NVD · CRITICAL
9.0CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Internet exposure
not stated by sourcesNo exposure census on this CVE's dispatches.

Exploits

1 known · links only

GitHub PoCs · by trust, then stars1

  1. murrez/CVE-2026-100721 ↗Trust ok 100

    CVE-2026-100721 PoC: vm2 <3.12.2 NodeVM external allowlist bypass → sandbox escape / host RCE. Local Node lab (evil-left-pad), remote sandbox API mass exploit, colorful CLI. PoCbit — https://pocbit.org/pocs/cve-2026-100721

    ★ 0 · created 2026-09-28

Fake proof-of-concept repositories have been used to deliver malware to the researchers who run them. The trust verdict is our engine's heuristic over the repository (account age, what it ships, how its stars arrived); it is a reason to read the code first, not a finding about its author.

On the wire

1 dispatch
  1. CVE-2026-100721: vm2 before 3.12.2 contains an authorization bypass in the NodeVM external-module resolver. …VULN

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