In Libav through 11.11 and 12.x through 12.1, the smackerdecodetree function in libavcodec/smacker.c does not properly restrict tree recursion, which allows remote attackers to cause a denial of service (bitstream.c:buildtable() out-of-bounds read and application crash) via a crafted Smacker stream.
libav before 12.1 is vulnerable to an invalid read of size 1 due to NULL pointer dereferencing in the nsvreadchunk function in libavformat/nsvdec.c.