The 0-day security issue has already been exploited in the wild on April 27, 2021, 15:23 Bottom line: Following a three-month beta, Apple has finally released a stable build of macOS 11.3 to the public, with several new features and a fix for a software bug that is known to have been exploited by malicious actors in the wild. Unless you're sticking with macOS Catalina for compatibility reasons, now would be a good idea to go to System Preferences > Software Update and update your Mac. The latest macOS Big Sur update includes a number of optimizations for those of you running iPhone or iPad apps on new M1-based Macs, including support for displaying the highest resolution version of those apps in full screen. Additionally, you can now resize the app window and map touch inputs to keyboard and mouse commands via a Touch Alternatives pane in the app preferences, as well as enable controller emulation via a Game Control pane.