Artifex MuPDF 1.11 allows attackers to execute arbitrary code or cause a denial of service via a crafted .xps file, related to a "User Mode Write AV near NULL starting at wow64!Wow64NotifyDebugger+0x000000000000001d" on Windows. This occurs because read_zip_dir_imp in fitz/unzip.c does not check whether size fields in a ZIP entry are negative numbers.