In GraphicsMagick 1.3.31, the ReadDIBImage function of coders/dib.c has a vulnerability allowing a crash and denial of service via a dib file that is crafted to appear with direct pixel values and also colormapping (which is not available beyond 8-bits/sample), and therefore lacks indexes initialization.
https://www.debian.org/security/2020/dsa-4640
https://usn.ubuntu.com/4207-1/
https://sourceforge.net/p/graphicsmagick/bugs/585/
https://lists.debian.org/debian-lts-announce/2018/12/msg00018.html
http://www.securityfocus.com/bid/106227
http://hg.graphicsmagick.org/hg/GraphicsMagick/rev/648e2b406589