If you have an iOS 12 device and want to jailbreak it, you have two potential alternatives available: Chimera by Electra Team and unc0ver by Pwn20wnd. Both can jailbreak iOS 12.0-12.3 beta, but the latter is particularly limited on A12 (X) devices because Cydia Substrate has not (and will not) be updated to work with them.
Electra Teams Chimera jailbreak works painlessly on A12 (X) handsets because it uses a Substitute implementation instead of Cydia Substrate. This was perhaps one of the most compelling reasons to use Chimera at the time, but as you may recall, Pwn20wnd worked to implement Substitute in the unsurpassed jailbreak, at least for A12 (X) devices.
While we have seen countless updates for both jailbreak tools in recent memory, it has been quite a while since we heard any updates regarding the status of a substitute-based unc0ver jailbreak for A12 (X) devices. Fortunately, Pwn20wnd broke the silence today via Twitter by sharing that he had made significant progress:
From What We Can Collect , Pwn20wnd has successfully implemented the backbone of Substitute in unc0ver, and as it seems, the hacker seems happy with its performance and stability.
Worth noting, Pwn20wnd mentions that Substitute is working "on all devices," which is a significant departure from the original plan to support only A12 (X) devices. Also, it appears that the substitute works on all firmware versions not supported by non-support on pre-A12 (X) devices, but only supports iOS 12.0-12.1.2 on A12 (X) devices at this time .
Pwn20wnd's Tweet mentions that most of the work is now complete, and it also appears that unc0ver can be updated with full A12 (X) compatibility in the near future. On the other hand, no stated ETA has been delivered.
As always, we will continue to keep you updated as relevant news for jailbreak. Keep it tuned here lately.