vm2 is a sandbox for running untrusted Node.js code. In versions >= 3.11.4 and <= 3.11.6, the NodeVM constructor computes hasRealRequireConfig with typeof requireOpts === 'object' && requireOpts !== null, so an array-shaped require value (for example require: []) satisfies the guard that is meant to reject nesting without an explicit require configuration. makeResolverFromLegacyOptions() then destructures the array into undefined option fields and returns a resolver containing only NESTING_OVERRIDE.vm2. As a result, an attacker who can supply JavaScript executed by a NodeVM configured with truthy nesting and an array-shaped require (e.g. new NodeVM({nesting: true, require: []})) can require the host vm2 module, create an inner NodeVM with an attacker-chosen builtin allowlist (such as…