You probably knew this already, but if you’ve got a jailbroken iPhone or iPad, don’t upgrade to iOS 8.3. Not only does it break existing jailbreaks, but it patches a huge number of security holes in the operating system, making an iOS 8.3 jailbreak farther off than ever.
As pointed out on Twitter by iOS jailbreak superstar MuscleNerd, the latest iOS 8.3 update comntains a staggering 39 security fixes. That, for the record, is about as many security fixes Apple made between iOS 7 and iOS 8.
It’s actually a huge accomplishment on Apple part. When iOS 8 was released, it could be jailbroken almost immediately. Jailbreakers kept up with Apple’s patches right up to iOS 8.1.2, but iOS 8.1.3 represented the first big stumbling block for jailbreakers trying to get around Apple’s defenses.
iOS 8.3 looks about as strong from a security standpoint as any version of iOS 8 ever. It even patches a vulnerability used by the TaiG Jailbreak Team, which many were hoping would result in a speedy iOS 8.3 jailbreak. (As a slight consolation prize, Apple credited the TaiG team for finding the bug in their support notes).