Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Exploitability
AV:NAC:LPR:NUI:RScope
S:UImpact
C:LI:LA:N5.4/CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N