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CVE-2026-100721: Product identification pending

Severity

9.5 (CRITICAL)

Vendor

VM2 BEFORE

Affected versions

Before 3.12.2

Fixed version

3.12.2

Patch status

Patched

Published

2026-09-27T02:17:17.547

Modified

2026-09-27T02:17:18.070

Why it matters

This matters because the affected product may allow code execution. Prioritize systems that are internet-facing or have privileged access to other infrastructure.

Recommended admin actions

• Prioritize validation immediately due to critical CVSS severity.
• Compare installed versions against the affected version range in the advisory.

Technical 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-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.

View the official NVD record for CVE-2026-100721

CVE data is sourced from NVD/CNA records and optional enrichment. Validate against the vendor advisory before taking production action.