PyMuPDF through 1.28.2, fixed in commit b2c8f3a, contains a path traversal vulnerability in the font branch of extract_objects() in src/main.py, where the output filename is constructed by joining a document-controlled BaseFont name directly onto the user-supplied output directory without stripping path separators or dot-dot sequences. Attackers can supply a crafted PDF, EPUB, XPS, or FB2 file with a BaseFont name containing encoded path separators that decode to ../ sequences or absolute paths, causing arbitrary file writes outside the intended output directory without requiring authentication or elevated privileges.