A jailbreak for iOS 8.4.1 could be in the works, speculate several postings on a Reddit discussion thread. Luca Todesco, an Italian developer, who runs the Twitter handle qwertyoruiop, claims that a jailbreak for iOS 8.4.1 is on the way. Although he was never a part of any major jailbreak release in past, he has created a few tweaks.
If you have accidentally upgraded to iOS 9, or the latest iOS 9.0.1 which Apple rolled out recently carrying a number of fixes and improvements, downgrade your iPhone or iPad to iOS 8.4.1 in favour of a jailbreak utility. The jail-breaker has not given the estimated time of arrival of the release but says it depends on several memory corruption bugs.
It is suggested that you perform the downgrade as soon as possible before Apple closes the signing window for iOS 8.4.1, which was the last iteration of iOS 8. Even after installing a jailbreak for iOS 8.4.1, you can upgrade to the latest iOS 9, but you will not be able to downgrade anymore once Apple stops signing the firmware.
Apple shut its iOS 8.4 firmware window (on 22 August), nine days after releasing iOS 8.4.1. The iOS 8.3 signing window was closed on 7 July seven days after iOS 8.4 was rolled out on 30 June. It is almost 10 days since Apple made iOS 9 available, so expect the firmware window to be closed any time now.
Even after Apple patched the exploits in iOS 9, which were discovered by the Pangu and TiaG jailbreak teams, qwertyoruiop asserts he has collected some vulnerabilities in iOS 9.
"Yep. I had stacked enough vulns to do it, and the most important stuff is present on iOS 9. I had been working on some very cool stuff for iOS 9; however the code sign bypass was mitigated (not patched). The thing w/ the codesign bypass (yet another segment overlap by the way) is that the specific code paths I need to use to map segments cannot be used anymore without codesigning (which defeats the point of the bug itself)," replies qwertyoruiop in response to a query related to iOS 9 jailbreak.
"Before iOS 9, code signatures were only verified after mapping all segments, which allowed you to easily defeat code signatures. Now they first check for the signature of segment commands, only then they use them for anything. I still have some cool ios9 stuff, but miss too many steps in the chain at this point."