Apple has just released the first of its new Rapid Security Responses (RSRs) for macOS 13.3.1 Ventura. This is indicated as macOS Rapid Security Response 13.3.1 (a), and is just just over 300 MB to download for Apple silicon Macs, and rather less for Intel models. This requires a restart to complete installation, but little additional time to a normal restart.

The only obvious change following installation of this RSR is that Safari has an incremented build number, from version 16.4 build 18615.1.26.11.23 to version 16.4 build 18615.1.26.110.1.

On completion, macOS is given as version 13.3.1 (a), with a build number of 22E772610a. If you decide you want to remove the RSR, click on the Info icon next to the macOS version number in System Settings > General > About. Further details are in this article.

Although you can use SilentKnight or the command tool softwareupdate to download the RSR, they appear unable to install it, leaving them apparently still connected to Apple’s software update server. If you end up with an endless busy cursor, open System Settings > General > Software Update, and click on the button there to install the RSR and restart your Mac. It’s simpler just to download and install the RSR from Software Update in the first place.

Last updated at 1750 on 1 May 2023.