Apple on Wednesday stopped signing code for iOS 9.3.2 and iOS 9.3.3, meaning device users who upgraded to the most recent iOS 9.3.4 version, or who have not yet upgraded from iOS 9.3.1, are no longer able to access the release.
Twitter bot @TSSstatus brought word of the change, which prevents users from installing a version of iOS susceptible to security breaches. The move also effectively blocks the Pangu jailbreaks for iOS 9.3.2 and iOS 9.3.3.
Apple pushed iOS 9.3.4 out earlier this month, calling the release an "important security update." An accompanying support document describing the contents of the security update noted a single memory corruption issue that could allow an application to execute arbitrary code. Team Pangu was credited for discovering -- and exploiting -- the vulnerability.
Apple first released iOS 9.3.2 in June with fixes for iPhone SE Bluetooth issues and the ability to use Night Shift in Low Power Mode. The update was pulled and re-released for the 9.7-inch iPad Pro after users complained of bricking issues.
iOS 9.3.3 was released as a maintenance update in July with a critical fix for a flaw resembling the Stagefright exploit that hit Google's Android platform last year. The vulnerability, discovered by a Cisco engineer, allowed for the surreptitious gathering of sensitive data with a text message.