Off-by-one error in the DrawImage function in magick/render.c in GraphicsMagick 1.3.26 allows remote attackers to cause a denial of service (DrawDashPolygon heap-based buffer over-read and application crash) via a crafted file.
https://lists.debian.org/debian-lts-announce/2018/06/msg00009.html
https://sourceforge.net/p/graphicsmagick/bugs/448/