In order to install apps that are not available on the App Store, you need to jailbreak the iPhone. With every iOS release, Apple makes it difficult to jailbreak with new security improvements. Yesterday, Unc0ver released a new jailbreaking tool that can jailbreak any iPhone running iOS version 11 or later. Once you jailbreak the device, you can install the popular 3rd party app stores AltStore and Cydia.
“This jailbreak basically just adds exceptions to the existing rules. It only enables reading new jailbreak files and parts of the filesystem that contain no user data,” said Unc0ver’s lead developer, who goes by Pwn20wnd.
Unc0ver also mentioned that this jailbreak mechanism doesn’t affect the core security model of iOS. This jailbreak is built on a zero-day vulnerability found in iOS. Also, Apple was not informed about this vulnerability before. So, until Apple releases a patch in the coming weeks, you can jailbreak your iPhone easily.