In the GetOpenCLCachedFilesDirectory function in magick/opencl.c in ImageMagick 7.0.7, a NULL pointer dereference vulnerability occurs because a memory allocation result is not checked, related to GetOpenCLCacheDirectory.
https://github.com/ImageMagick/ImageMagick/issues/790
https://lists.debian.org/debian-lts-announce/2020/09/msg00007.html