Apple supports two predecessor systems alongside the current version of macOS, and an important security update for macOS 10.14 (Mojave) and 10.15 (Catalina) was rolled out at the same time as yesterday's Big Sur 11.2 update.
The update in question is called Security Update 2021-001 for macOS Catalina 10.15.7 and Security Update 2021-001 for macOS Mojave 10.14.6; users can download these from the Software Update section in the system settings.
With this security update, Apple has closed a number of loopholes that could have compromised Catalina owners specifically, although the company recommends that users of all compatible systems install the update, which closes a kernel bug that gives attackers more rights in the system.
Apple says the bug has already been exploited for attacks in the wild. It is therefore a zero-day gap if the person who found the error does not notify the manufacturer in good time, but instead exploits it on current systems.
The same vulnerability (CVE-2021-1782) can also be found in older versions of iOS and iPadOS. Apple fixed it on mobile systems last week with the updates to iOS 14.4 and iPadOS 14.4. These updates are also strongly recommended.
For broader advice read our Mac security tips.
This article originally appeared on Macwelt. Translation by David Price.