Apple's devices are famous for their security, but they aren't infallible and Apple's latest update to Safari revealed that a vulnerability in the browser "may have been actively exploited."
The flaw could be leveraged by hackers to "execute arbitrary code with kernel privileges," which effectively means they could run any command they wanted with full system privileges. This affects virtually all of Apple's platforms, so if you own an iPhone, iPad, MacBook, iMac, or Mac mini you need to make sure that you have downloaded and installed the latest OS update (via MacRumors).
How to install the latest update to iOS or iPadOS
iOS 15.6.1 and iPadOS 15.6.1 are the most up-to-date versions available for iPhone 6s and later, iPad Pro, iPad Air 2 and later, iPad 5th gen and later, iPad mini 4 and later, and iPod Touch 7th gen.
To ensure you have the latest update installed you need to go to Settings > General and then tap Software Update. If an update is available then tap on it to download and install.
How to install the latest update to macOS
The latest update available for Mac laptops and desktops is macOS Monterey 12.5.1. To ensure that you have the latest version of macOS installed click on the Apple menu > System Preferences and then click Software Update. If an update is available click on it to download and install it immediately.
Whether you are on macOS Monterey or Big Sur you should also make sure you are updated to the latest version of Safari, 15.6.1. This update will also be displayed on the Software Update screen, so just make sure you don't skip it.
That's it, once you have all of the updates installed your Apple device(s) should be secure once again.