A use-after-free vulnerability can occur after deleting a selection element due to a weak reference to the select element in the options collection. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.4, Firefox ESR < 60.4, and Firefox < 64.
https://www.mozilla.org/security/advisories/mfsa2018-31/
https://www.mozilla.org/security/advisories/mfsa2018-30/
https://www.mozilla.org/security/advisories/mfsa2018-29/
https://www.debian.org/security/2019/dsa-4362
https://www.debian.org/security/2018/dsa-4354
https://usn.ubuntu.com/3868-1/
https://usn.ubuntu.com/3844-1/
https://security.gentoo.org/glsa/201903-04
https://lists.debian.org/debian-lts-announce/2018/12/msg00002.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1499861
https://access.redhat.com/errata/RHSA-2019:0160
https://access.redhat.com/errata/RHSA-2019:0159
https://access.redhat.com/errata/RHSA-2018:3833