The vc1_decode_frame function in libavcodec/vc1dec.c in Libav 12.2 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted file.
https://lists.debian.org/debian-lts-announce/2019/12/msg00003.html
https://deb.freexian.com/extended-lts/tracker/CVE-2017-17127