Due to an error on Apple’s part, it was after years that we saw a jailbreak being available for the latest public release of iOS. While Unc0ver and Chimera have both been updated to jailbreak iOS 12.4, they both lack support for A12/X Bionic devices like the iPhone XS and iPhone XR.
The @pwn20wnd team did update Unc0ver earlier this week with partial support for A12/X devices. But that’s not going to be enough because while one can theoretically jailbreak their iPhone XS or iPhone XR using the tool, the lack of a PAC bypass means they cannot install Cydia or jailbreak tweaks on it.
Thanks to the hard work of the @pwn20wnd team though, we might just see a full-fledged iOS 12.4 jailbreak for iPhone XS, iPhone XR, and the 2018 iPad Pro. The team has been steadily working on this front and has made quite a bit of inroad over the last 24 hours.
As evident from the tweets, the team behind Unc0ver are not looking for a PAC bypass due to the level of difficulty involved. Instead, they are working on an alternate unsigned code execution method for a full-fledged iOS 12.4 jailbreak for A12/X Bionic devices. Don’t get your hopes too high though as there is still plenty of work left that needs to be done. Most importantly, the team needs to figure out how to remount RootFS without PAC bypass as it is after that they can get jailbreak tweaks to work on a jailbroken A12/X Bionic iOS device.
Successfully got the unsigned code execution method I got working with @Jakeashacks implemented in the jailbreak — I can now arbitrarily execute unsigned binaries and run sideloaded apps with expired certificates on A12-A12X without PAC bypass!
— @Pwn20wnd (@Pwn20wnd) August 21, 2019
Next step is remounting RootFS without PAC bypass — Once that's done, you know what comes next ;).
— @Pwn20wnd (@Pwn20wnd) August 21, 2019
Successfully got SSH/root-shell running on A12 without kernel-code-execution/PAC bypass!
— @Pwn20wnd (@Pwn20wnd) August 22, 2019
I don’t know when — if at all — we will see a fully working iOS 12.4 jailbreak for iPhone XS, iPhone XR, and other A12/X Bionic devices. What I do know is that the hard work being done by the Pwn20wnd team here is commendable and deserves a lot of respect from the community.
