The ReadTXTImage function in coders/txt.c in ImageMagick through 6.9.9-0 and 7.x through 7.0.6-1 allows remote attackers to cause a denial of service (infinite loop) via a crafted file, because the end-of-file condition is not considered.
https://bugs.debian.org/869210
https://github.com/ImageMagick/ImageMagick/commit/83e0f8ffd7eeb7661b0ff83257da23d24ca7f078
https://github.com/ImageMagick/ImageMagick/commit/a8f9c2aabed37cd6a728532d1aed13ae0f3dfd78
https://github.com/ImageMagick/ImageMagick/issues/591
https://lists.debian.org/debian-lts-announce/2019/05/msg00015.html