Apple has released macOS Catalina 10.15.6, along with Security Update 2020-004 Mojave, and Security Update 2020-004 High Sierra.
MacOS Catalina 10.15.6 includes several bug fixes and security patches, and the Security Update 2020-004 for Mojave and High Sierra both include important security fixes for Mac users running macOS Mojave and macOS High Sierra.
Separately, Apple also released updates of iOS 13.6 for iPhone and iPadOS 13.6 for iPad, along with small updates to watchOS and tvOS.