FFmpeg 4.2 is affected by a Divide By Zero issue via libavcodec/aaccoder, which allows a remote malicious user to cause a Denial of Service
https://www.debian.org/security/2021/dsa-4998
https://www.debian.org/security/2021/dsa-4990
https://trac.ffmpeg.org/ticket/8003
https://lists.debian.org/debian-lts-announce/2021/11/msg00012.html