In ImageMagick 7.0.6-3, missing validation was found in coders/mat.c, leading to an assertion failure in the function DestroyImage in MagickCore/image.c, which allows attackers to cause a denial of service.
https://usn.ubuntu.com/3681-1/
https://lists.debian.org/debian-lts-announce/2020/09/msg00007.html
https://lists.debian.org/debian-lts-announce/2019/05/msg00015.html