ImageMagick 7.0.7-26 Q16 has excessive iteration in the DecodeLabImage and EncodeLabImage functions (coders/tiff.c), which results in a hang (tens of minutes) with a tiny PoC file. Remote attackers could leverage this vulnerability to cause a denial of service via a crafted tiff file.
https://usn.ubuntu.com/3681-1/
https://lists.debian.org/debian-lts-announce/2020/08/msg00030.html