Severity: Critical
CVSS Score: 9.8
Use-after-free vulnerability in the nsRefreshDriver::Tick function in Mozilla Firefox before 49.0, Firefox ESR 45.x before 45.4, and Thunderbird < 45.4 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) by leveraging improper interaction between timeline destruction and the Web Animations model implementation.