The ff_rv34_decode_init_thread_copy function in libavcodec/rv34.c in FFmpeg before 2.7.2 does not initialize certain structure members, which allows remote attackers to cause a denial of service (invalid pointer access) or possibly have unspecified other impact via crafted (1) RV30 or (2) RV40 RealVideo data.
http://ffmpeg.org/security.html
http://git.videolan.org/?p=ffmpeg.git;a=commit;h=3197c0aa87a3b7190e17d49e6fbc7b554e4b3f0a
http://www.securitytracker.com/id/1033483
http://www.ubuntu.com/usn/USN-2944-1
https://lists.debian.org/debian-lts-announce/2018/12/msg00009.html