Does MuPDF use openjp (version 2.1.1) ? Because that library have a vulnerability when open a JPEG2000 picture. That also affect PDF files too. Read here for more details: http://www.talosintelligence.com/reports/TALOS-2016-0193/
The latest version of MuPDF (from Git) uses 2.1.2, where this is fixed.
Nice! It would be great if we can get that build as executable then.