The gmc_mmx function in libavcodec/x86/mpegvideodsp.c in FFmpeg 2.3 and 3.4 does not properly validate widths and heights, which allows remote attackers to cause a denial of service (integer signedness error and out-of-array read) via a crafted MPEG file.
Exploitability
AV:NAC:LPR:NUI:RScope
S:UImpact
C:NI:NA:H6.5/CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H