Apple has released the macOS Catalina 10.15.7 Supplemental Update, which includes several security fixes for your Mac. You can get the details of the update in Apple’s macOS Catalina 10.15.7 Supplemental Update support document.
Before installing the update, it’s a good idea to back up your Mac’s data in case the update causes an issue with your software and you need to restore. Here’s how to install the update.
Click on the Apple menu and select About This Mac.
Click on the Software Update button that appears in the Overview tab.
The Software Update system preference should open. Click the Update Now button when you are ready.
Your Mac will need to restart.
Source : Macworld