In ImageMagick 7.0.7-16 Q16, a vulnerability was found in the function ReadOnePNGImage in coders/png.c, which allows attackers to cause a denial of service (ReadOneMNGImage large loop) via a crafted mng image file.
https://github.com/ImageMagick/ImageMagick/issues/908
https://lists.debian.org/debian-lts-announce/2018/01/msg00000.html
https://lists.debian.org/debian-lts-announce/2019/05/msg00015.html
https://lists.debian.org/debian-lts-announce/2020/09/msg00007.html