Integer overflow in the get_len function in libavutil/lzo.c in FFmpeg before 0.10.14, 1.1.x before 1.1.12, 1.2.x before 1.2.7, 2.0.x before 2.0.5, 2.1.x before 2.1.5, and 2.2.x before 2.2.4 allows remote attackers to execute arbitrary code via a crafted Literal Run.
In FFmpeg before 4.2, avcodec_open2 in libavcodec/utils.c allows a NULL pointer dereference and possibly unspecified other impact when there is no valid close function pointer.
FFmpeg through 4.2 has a "Conditional jump or move depends on uninitialised value" issue in h2645_parse because alloc_rbsp_buffer in libavcodec/h2645_parse.c mishandles rbsp_buffer.
aa_read_header in libavformat/aadec.c in FFmpeg before 3.2.14 and 4.x before 4.1.4 does not check for sscanf failure and consequently allows use of uninitialized variables.
libavcodec/hevcdec.c in FFmpeg 3.4 and 4.1.2 mishandles detection of duplicate first slices, which allows remote attackers to cause a denial of service (NULL pointer dereference and out-of-array access) or possibly have unspecified other impact via crafted HEVC data.
The studio profile decoder in libavcodec/mpeg4videodec.c in FFmpeg 4.0 before 4.0.4 and 4.1 before 4.1.2 allows remote attackers to cause a denial of service (out-of-array access) or possibly have unspecified other impact via crafted MPEG-4 video data.
In FFmpeg 3.2 and 4.1, a denial of service in the subtitle decoder allows attackers to hog the CPU via a crafted video file in Matroska format, because ff_htmlmarkup_to_ass in libavcodec/htmlsubtitles.c has a complex format argument to sscanf.