In the mxf_read_primer_pack function in libavformat/mxfdec.c in FFmpeg 3.3.3, an integer signedness error might occur when a crafted file, which claims a large item_num field such as 0xffffffff, is provided. As a result, the variable item_num turns negative, bypassing the check for a large value. https://nvd.nist.gov/vuln/detail/CVE-2017-14169
