Wednesday saw Apple stop signing iOS 9.3.2 and iOS 9.3.3 on the iPhone, iPad, and iPod touch. This means users can no longer upgrade or downgrade to either of those versions of iOS via iTunes. Currently, the only public version of iOS Apple is signing is iOS 9.3.4.
Wednesday’s move also effectively blocks the Pangu jailbreaks for iOS 9.3.2 and iOS 9.3.3, as it is no longer possible for iOS users to downgrade to either of the iOS versions compatible with the jailbreak. (iOS 9.3.4 fixes a security hole used by Pangu to pull off the jailbreak.)
iOS 9.3.2 was released by Apple in June, and contained fixes for iPhone SE Bluetooth issues and the ability to use Night Shift in Low Power Mode. When 9.7-inch iPad Pro users complained that the update was bricking their devices, Apple pulled the update for those devices, later releasing a fixed version of the update.
iOS 9.3.3 was released as a maintenance update in July offering a fix for a critical security flaw similar to last year’s Stagefright bug which afflicted Android devices, and could allow an attacker access to a device’s stored passwords and files simply by sending a user a malicious image file.