libavcodec/webp.c in FFmpeg before 2.8.12, 3.0.x before 3.0.8, 3.1.x before 3.1.8, 3.2.x before 3.2.5, and 3.3.x before 3.3.1 does not ensure that pix_fmt is set, which allows remote attackers to cause a denial of service (heap-based buffer overflow and application crash) or possibly have unspecified other impact via a crafted file, related to the vp8_decode_mb_row_no_filter and pred8x8_128_dc_8_c functions.
https://lists.debian.org/debian-lts-announce/2019/01/msg00006.html
https://github.com/FFmpeg/FFmpeg/commit/6b5d3fb26fb4be48e4966e4b1d97c2165538d4ef
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=1435