In the function ReadTXTImage() in coders/txt.c in ImageMagick 7.0.6-10, an integer overflow might occur for the addition operation "GetQuantumRange(depth)+1" when "depth" is large, producing a smaller value than expected. As a result, an infinite loop would occur for a crafted TXT file that claims a very large "max_value" value.
https://usn.ubuntu.com/3681-1/
https://security.gentoo.org/glsa/201711-07
https://lists.debian.org/debian-lts-announce/2020/09/msg00007.html
https://lists.debian.org/debian-lts-announce/2019/05/msg00015.html
https://github.com/ImageMagick/ImageMagick/commit/50f54462076648ac2e36c3f58f4dadd4babbf1c9