There are 2 open security issues in buster.
2 issues left for the package maintainer to handle:
Artifex MuPDF before 1.18.0 has a heap based buffer over-write in tiff_expand_colormap() function when parsing TIFF files allowing attackers to cause a denial of service.
MuPDF through 1.18.1 has an out-of-bounds write because the cached color converter does not properly consider the maximum key size of a hash table. This can, for example, be seen with crafted "mutool draw" input.
You can find information about how to handle these issues in the security team's documentation.