CVE 2018-12377
A use-after-free vulnerability can occur when refresh driver timers are refreshed in some circumstances during shutdown when the timer is deleted while still in use. This results in a potentially exploitable crash. This vulnerability affects Firefox < 62, Firefox ESR < 60.2, and Thunderbird < 60.2.1.
See the 
CVE page on Mitre.org
for more details.
