FFmpeg 2.8 and 4.2.3 has a use-after-free via a crafted EXTINF duration in an m3u8 file because parse_playlist in libavformat/hls.c frees a pointer, and later that pointer is accessed in av_probe_input_format3 in libavformat/format.c.
https://www.debian.org/security/2020/dsa-4722
https://usn.ubuntu.com/4431-1/
https://trac.ffmpeg.org/ticket/8673
https://security.gentoo.org/glsa/202007-58
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20200529033905.41926-1-lq%40chinaffmpeg.org/
https://lists.debian.org/debian-lts-announce/2020/07/msg00022.html
https://github.com/FFmpeg/FFmpeg/commit/6959358683c7533f586c07a766acc5fe9544d8b2