Host code execution via Promise species bypass

Code injection in Patrik Simek vm2 3.9.19 and earlier allows attackers to escape the sandbox and execute arbitrary host code. The Promise.prototype.then wrapper sanitizes rejection handlers but trusts a promise constructor's Symbol.species, letting an attacker-supplied constructor receive an unsanitized host exception. Exploitation requires the application to execute attacker-controlled asynchronous JavaScript inside a vm2 sandbox; escaped code runs with the host Node.js process's privileges.