In ImageMagick 7.0.7-23 Q16 x86_64 2018-01-24, there is a heap-based buffer over-read in ReadSUNImage in coders/sun.c, which allows attackers to cause a denial of service (application crash in SetGrayscaleImage in MagickCore/quantize.c) via a crafted SUN image file.
https://www.debian.org/security/2018/dsa-4245
https://usn.ubuntu.com/3681-1/
https://lists.debian.org/debian-lts-announce/2018/06/msg00004.html
https://lists.debian.org/debian-lts-announce/2018/05/msg00012.html