Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.
https://www.tenable.com/blog/how-covid-19-response-is-expanding-the-cyberattack-surface
https://www.mozilla.org/security/advisories/mfsa2020-04/
https://www.mozilla.org/security/advisories/mfsa2020-03/
https://usn.ubuntu.com/4335-1/
https://security.gentoo.org/glsa/202003-02
https://bugzilla.mozilla.org/show_bug.cgi?id=1607443
http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html