PangGu and TaiG are the two teams that were able to jailbreak Apple's iOS 8.4.1, and in an official post on the Apple support page, they were credited for discovering a big security flaw in iOS 9. According to the post, the security flaw has since been addressed through "improved bounds checking." 

The developer teams discovered that an app could be made to bypass the code signing in iOS 9, which meant anyone could hack into a person's iPhone or iPad. The issue was apparent on the iPhone 4s and later models, the iPad 2 and later models, and the fifth generation of the iPod touch. 

Both teams still have their official pages up to allow anyone still using iOS 8.4.1 to jailbreak their device. There are also rumors that it is possible to downgrade from iOS 9 to iOS 8.4.1 in order to jailbreak as there is no official jailbreak support at the time being for the latest iOS version. 

However, after jailbreaking iOS 8.4.1, there are several things that a phone or tablet user must not do in order to prevent their phone from breaking. This includes deleting system files, installing too many jailbreak tweaks that could force a user to restore their phone back to its factory setting, and forcing the phone to update, which would render the jailbreak useless. 

While PangGu and TaiG have not yet released an official jailbreak system for iOS 9, developer Steven De Franco aka iH8snow shows in a YouTube video that he has been able to jailbreak through the iOS 9 Gold Master version.

However, the jailbreak was revealed before the official release of the OS and it is possible that Apple may have already patched the final version that would make iH8snow's process no longer viable. iH8snow has also made no announcements of releasing the jailbreak system to the public at this point in time.