A use-after-free vulnerability can occur in the compositor during certain graphics operations when a raw pointer is used instead of a reference counted one. This results in a potentially exploitable crash. This vulnerability affects Firefox ESR < 52.7.3 and Firefox < 59.0.2.
https://www.mozilla.org/security/advisories/mfsa2018-10/
https://www.debian.org/security/2018/dsa-4153
https://usn.ubuntu.com/3609-1/
https://lists.debian.org/debian-lts-announce/2018/03/msg00023.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1440717
https://access.redhat.com/errata/RHSA-2018:1099
https://access.redhat.com/errata/RHSA-2018:1098