Mozilla developers and community members reported memory safety bugs present in Firefox 62 and Firefox ESR 60.2. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Firefox < 63, Firefox ESR < 60.3, and Thunderbird < 60.3.
https://www.mozilla.org/security/advisories/mfsa2018-28/
https://www.mozilla.org/security/advisories/mfsa2018-27/
https://www.mozilla.org/security/advisories/mfsa2018-26/
https://www.debian.org/security/2018/dsa-4337
https://www.debian.org/security/2018/dsa-4324
https://usn.ubuntu.com/3868-1/
https://usn.ubuntu.com/3801-1/
https://security.gentoo.org/glsa/201811-13
https://security.gentoo.org/glsa/201811-04
https://lists.debian.org/debian-lts-announce/2018/11/msg00011.html
https://lists.debian.org/debian-lts-announce/2018/11/msg00008.html
https://access.redhat.com/errata/RHSA-2018:3532
https://access.redhat.com/errata/RHSA-2018:3531
https://access.redhat.com/errata/RHSA-2018:3006
https://access.redhat.com/errata/RHSA-2018:3005
http://www.securitytracker.com/id/1041944