According to Dev Team, there are 3 separate untethered jailbreaks simultaneously that all use different methods. Hardware (A5/A5X) must have a flaw to allow them to gain a foothold via USB. Software exploit that enables the untethers are usually both hardware or software. Unbreakable hardware always will be jailbreakable, but untethering is much more elusive, says Dev Team. The most exciting detail is that there are three separate untether jailbreaks using different ways.”]
Source: https://gizmodo.com/hackers-jailbreak-new-ipad-just-a-few-hours-after-relea-5894043