---
id: CVE-2026-100721
title: >-
  vm2 before 3.12.2 contains an authorization bypass in the NodeVM
  external-module resolver
summary: >-
  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-comp…
severity: critical
cvss: 9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-863
vendor: patriksimek
product: vm2
affected:
  - vm2 < 3.12.2
published: '2026-09-27'
updated: '2026-09-28'
sourceUpdated: '2026-09-28T17:17:46.057'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100721'
references:
  - url: >-
      https://github.com/patriksimek/vm2/commit/6ac3916da84e060c403e407b6b6318fcc66b0e72
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/patriksimek/vm2/commit/91034466bfb7f56b95fd48083ec6ca36d058f164
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/patriksimek/vm2/commit/ab4ee7d803e8c80155e9eb3672226bddbca4aa9c
    label: disclosure@vulncheck.com
  - url: 'https://github.com/patriksimek/vm2/security/advisories/GHSA-5h3f-q97h-ccvc'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/vm2-before-3.12.2-authorization-bypass-via-custom-resolver
    label: disclosure@vulncheck.com
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100721'
  - url: >-
      https://github.com/patriksimek/vm2/commit/fb4977f6211da6cadffdf1f3a2017a826a21c51f
  - url: 'https://github.com/patriksimek/vm2/releases/tag/v3.12.2'
  - url: 'https://github.com/advisories/GHSA-5h3f-q97h-ccvc'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100721.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-100721'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2541992'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-100721'
  - url: 'https://access.redhat.com/errata/RHSA-2026:88200'
tags:
  - nvd
  - exploit-available
  - cve.org
  - ghsa
  - npm
  - csaf
  - vex
  - red-hat
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/murrez/CVE-2026-100721'
  checkedAt: '2026-10-27T16:52:20.325Z'
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-28T16:50:50.404410Z'
ingestedAt: '2026-09-27T02:41:45.564Z'
epss: 0.00591
epssPercentile: 0.48058
aliases:
  - GHSA-5h3f-q97h-ccvc
ecosystem: npm
patched:
  - vm2 3.12.2
scores:
  nvd: 9
  ghsa: 10
  vendor: 9
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-100721)

Affected packages:

- `vm2 <= 3.12.1`

Patched in:

- `vm2 3.12.2`

Source: https://github.com/advisories/GHSA-5h3f-q97h-ccvc

## Vendor advisories

- **Red Hat VEX** · Critical · affected: Self-service automation portal 2 · no fix planned: Self-service automation portal 2 · updated 2026-10-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100721.json)
- **RHSA-2026:88200** · Red Hat · fixed in: Red Hat Ansible Automation Platform 2.2 · released 2026-10-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:88200)