In ImageMagick 7.0.7-16 Q16 x86_64 2017-12-21, there is a heap-based buffer over-read in ReadOneMNGImage in coders/png.c, related to length calculation and caused by an off-by-one error.
Exploitability
AV:NAC:LPR:NUI:RScope
S:UImpact
C:HI:HA:H8.8/CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H