In GraphicsMagick 1.3.27, there is an infinite loop and application hang in the ReadBMPImage function (coders/bmp.c). Remote attackers could leverage this vulnerability to cause a denial of service via an image file with a crafted bit-field mask value.
https://www.debian.org/security/2018/dsa-4321
https://sourceforge.net/p/graphicsmagick/bugs/541/
https://lists.debian.org/debian-lts-announce/2018/08/msg00002.html
https://lists.debian.org/debian-lts-announce/2018/01/msg00018.html
http://hg.graphicsmagick.org/hg/GraphicsMagick/rev/52a91ddb1aa6