A memory corruption issue was addressed with improved state management. This issue is fixed in macOS Big Sur 11.0.1, iTunes for Windows 12.10.9. Processing a maliciously crafted text file may lead to arbitrary code execution.
https://support.apple.com/kb/HT211935
https://support.apple.com/kb/HT211850
https://support.apple.com/kb/HT211844
https://support.apple.com/kb/HT211843
https://support.apple.com/en-us/HT211952