The ReadTIFFImage function in coders/tiff.c in ImageMagick 7.0.7-23 Q16 does not properly validate the amount of image data in a file, which allows remote attackers to cause a denial of service (memory allocation failure in the AcquireMagickMemory function in MagickCore/memory.c).
https://usn.ubuntu.com/3681-1/
https://lists.debian.org/debian-lts-announce/2020/08/msg00030.html
https://lists.debian.org/debian-lts-announce/2018/02/msg00028.html