Apple stopped signing the iOS 14.7.1 code on Monday, thus ending the downgrade operation from iOS 14.8 and the recently released iOS 15. Apple released iOS 14.7.1 in late July as a patch to solve the problem that Apple Watch cannot be unlocked by iPhone with Touch ID.
More importantly, the patch also fixes a security vulnerability that allows attackers to execute arbitrary code with kernel privileges. According to reports, the security vulnerability was used in a zero-click attack deployed in the Pegasus hacking tool of NSO Group.
After the new iOS system is released, Apple will usually stop signing traditional codes to protect customers from evil attempts to exploit newly discovered vulnerabilities. Preventing users from downloading old code also allows Apple to allow more iOS devices to use the latest, feature-rich software.
iOS 15 released by Apple on Monday has a series of new features, improvements and user interface adjustments. New features include real-time text and visual query, focus, upgraded Apple Maps, health application updates, iCloud+ integration, Safari browser redesign, and more.
The latest iOS 14 version, iOS 14.8, was released last week to fix another vulnerability exploited by Peg ASUS. Apple said earlier this year that for various reasons, it will not automatically push iOS 15 to users, and pointed out that it will continue to provide security updates for iOS 14 after the launch of the new operating system. Users who are still using iOS 14 will see two software update options in the settings, one is the latest iOS 14 version with bug fixes, and the other is iOS 15.