Meltdown and Spectre security risks affecting nearly every modern processor came to light last week, and now Apple has released a pair of software updates to address the Spectre vulnerability. iOS 11.2.2 and macOS High Sierra 10.13.2, while sparse in detail, are both now available for free on compatible devices.
iOS 11.2.2 for iPhone and iPad contains security fixes that aren't fully fleshed out, but Apple does say that they affect Safari and Webkit to "mitigate the effects of Spectre." Apple claims the Meltdown vulnerability was addressed in iOS 11.2, and since there isn't a hardware fix for Spectre, the company issued this over-the-air update to all compatible devices. iOS 11.2.2 is available for iPhone 5s and later, iPad Air and later, and iPod touch 6th generation. It can be downloaded by navigating to Settings > General > Software Update.