cbs_jpeg_split_fragment in libavcodec/cbs_jpeg.c in FFmpeg 4.1 and 4.2.2 has a heap-based buffer overflow during JPEG_MARKER_SOS handling because of a missing length check.
https://www.debian.org/security/2020/dsa-4722
https://usn.ubuntu.com/4431-1/
https://security.gentoo.org/glsa/202007-58
https://github.com/FFmpeg/FFmpeg/commit/a3a3730b5456ca00587455004d40c047f7b20a99
https://github.com/FFmpeg/FFmpeg/commit/1812352d767ccf5431aa440123e2e260a4db2726