In GraphicsMagick 1.4 snapshot-20190322 Q8, there is a heap-based buffer over-read in the ReadMNGImage function of coders/png.c, which allows attackers to cause a denial of service or information disclosure via an image colormap.
Exploitability
AV:NAC:LPR:NUI:RScope
S:UImpact
C:HI:NA:H8.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H