ReadRLEImage in coders/rle.c in GraphicsMagick 1.3.26 mishandles RLE headers that specify too few colors, which allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash) via a crafted file.
hg.graphicsmagick.org/hg/GraphicsMagick?cmd=changeset%3Bnode=5381c71724e3
lists.debian.org/debian-lts-announce/2018/06/msg00009.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PF62B5PJA2JDUOCKJGUQO3SPL74BEYSV/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WHIKB4TP6KBJWT2UIPWL5MWMG5QXKGEJ/
sourceforge.net/p/graphicsmagick/bugs/458/
usn.ubuntu.com/4232-1/
www.debian.org/security/2018/dsa-4321