On Monday, August 26, Apple quietly released iOS 12.4.1. This is a small update that came out a month after the release of iOS 12.4.
The iOS 12.4.1 update is available for all iOS 12 compatible devices. You can download it "over the air" by going to Settings, then opening the General section and clicking on the Software Update button. This is a small update, primarily aimed at fixing the vulnerability that allowed to jailbreak iOS 12.4. This vulnerability in the iOS 12.4 security system made mobile devices vulnerable to hacking, and, therefore, Apple dealt with it in the shortest possible time.