Pdfminer.six is a community maintained fork of the original PDFMiner, a tool for extracting information from PDF documents. Prior to version 20251107, pdfminer.six will execute arbitrary code from a malicious pickle file if provided with a malicious PDF file. The "CMapDB._load_data()" function in pdfminer.six uses "pickle.loads()" to deserialize pickle files. These pickle files are supposed to be part of the pdfminer.six distribution stored in the "cmap/" directory, but a malicious PDF can specify an alternative directory and filename as long as the filename ends in ".pickle.gz". A malicious, zipped pickle file can then contain code which will automatically execute when the PDF is processed. Version 20251107 fixes the issue.