CVE-2026-92951: vm2 Custom Module Resolver Can Bypass the External Package Allowlist by Loading a Colliding Host Package

vm2 is a sandbox library for isolating and executing untrusted JavaScript code inside a Node.js process. It can restrict access to built-in modules and external packages.

When NodeVM enables an external allowlist together with a custom resolve callback, vm2 checks the requested package name with a non-exact match. For example, if the allowlist only permits left-pad, an attacker can still bypass the check with a colliding package name such as evil-left-pad, because it contains the allowlisted name.

If the colliding package already exists in a host path resolvable by the custom resolver, or if the target application’s custom resolver / dependency-management workflow downloads the package and places it in a resolvable path, vm2 loads and executes that package in the host context. This lets sandboxed code bypass the module allowlist and may further lead to host code execution.