Apple just introduced an update to iOS 12.4 that likely fixes a security flaw that allowed a jailbreak to be created for this version — the first in years.
There don’t appear to be any other changes in iOS 12.4.1.
A brief history of jailbreaking
Apple has always insisted that third-party software come only through its App Store. In the early days of the iPhone, hackers would find ways around this restriction, allowing the installation of applications that wouldn’t pass Apple’s strict guidelines, as well as themes, tweaks and more. This was called jailbreaking.
Interest in it has nearly died out for three reasons. For one, the features that were once only available to a jailbroken phone — like video recording, useful settings toggles, custom ringtones and enhanced multitasking — are now part of iOS.
The second reason is that companies like Apple will pay $1 million or more for information about bugs that give attackers access to iPhones. So instead of creating a jailbreak, a hacker can buy a Lamborghini.
The third reason jailbreaking is dying is that Apple made its operating system so ironclad that hacking it has become very difficult.
But that changed last month. Apple left a security flaw in iOS 12.4 that allowed a full jailbreak for this version to be created.
Thus iOS 12.4.1
Closing this loophole seems to be the whole reason for iOS 12.4.1. Apple is just about to introduce iOS 13, so the company wouldn’t ordinarily be putting any effort into iOS 12.
iPhone and iPad users can install this version in either of the usual ways: hook their mobile device to a computer running iTunes, or down load the update directly. This can be done by going to Settings > General > Software Update.