Catalina 10.15.6 update is now available, with Mojave and High Sierra Security Updates 2020-004

Apple has just released what is expected to be the last substantial update to macOS 10.15 Catalina, bringing it to version 10.15.6. At only 3.35 GB, this is a relatively small update, which Apple states adds an option to optimise video streaming to improve battery life on compatible laptops, fixes issues where some USB mice and trackpads become disconnected, and another where the computer name can change after an update.

Apple promises more detail here, although it isn’t available yet.

This brings firmware updates for all recent models, for T2-equipped Macs taking their firmware to 1037.147.1.0.0 (iBridge: 17.16.16065.0.0,0). I have now updated my firmware databases for SilentKnight, and those kept here for browsing.

Security fixes are few in number, and include a couple for crafted audio files, with just one kernel fix. Full details are here.

For Catalina users (at least), this update brings an update to the KEXT data file, taking it to version 15.6.1.

At the same time, Apple has released Security Update 2020-004 for Mojave and High Sierra, which may be the last security update for 10.13. These are also accompanied by firmware updates for recent models, although the oldest supported Macs haven’t received updates.

Standalone installers are now available for:

I am very grateful to Pico for providing information on firmware updates and the standalone locations.