https://www.bleepingcomputer.com/news/security/microsoft-fixes-windows-certificate-spoofing-bug-abusing-cat-files/ > Microsoft's October 2020 Patch Tuesday fixed 87 security bugs, one of which is an "Important" Windows Spoofing Vulnerability that abuses CAT files. > The vulnerability enables attackers to create "polyglot malware," which merges different file types, to spoof digital signatures.