A heap-based Buffer Overflow vulnerability exits in FFmpeg 4.2 in deflate16 at libavfilter/vf_neighbor.c, which might lead to memory corruption and other potential consequences.
https://www.debian.org/security/2021/dsa-4990
https://trac.ffmpeg.org/ticket/8242
https://trac.ffmpeg.org/attachment/ticket/8242/gdb-vf_neighbor_191