Integer underflow in the nsHtml5TreeBuilder class in the HTML5 string parser in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) by leveraging

JIT code allocation can allow for a bypass of ASLR and DEP protections leading to potential memory corruption attacks. This vulnerability affects Thunderbird < 45.7, Firefox ESR < 45.7, and Firefox < 51.