Apple stops signing iOS 13.5.1, halting downgrades from iOS 13.6

Apple stopped signing iOS & iPadOS 13.5.1 Wednesday evening, a move on the company’s part that effectively prevents iPhone and iPad users from downgrading from the newer 13.6 release that was released to the general public exactly one week ago from today.

The company is notorious for preventing firmware downgrades because it doesn’t want users downgrading to versions that are vulnerable to exploits – whether those exploits are being used maliciously or for the sake of jailbreaking. Compelling users to upgrade to newer firmware when restoring also buffs Apple’s new firmware adoption statistics that the company frequently enjoys flaunting at Keynote presentations.

In this particular instance, a software-based jailbreak wasn’t specifically available for iOS or iPadOS 13.5.1. Only the unpatchable hardware-based checkra1n jailbreak supported iOS & iPadOS 13.5.1, and this of course only applied to A7-A11 devices that were vulnerable to the checkm8 bootrom exploit that powers it. That said, Wednesday’s change doesn’t impact the jailbreak community as much as an unsigned firmware usually would.

At this time, software-based jailbreaks including unc0ver and the upcoming Odyssey tool only support up to iOS & iPadOS 13.5, which was unsigned well over a month ago. No tfp0 exploits have been released for the current iOS & iPadOS 13.6 release as of yet, however one was recently teased by Twitter user @_Simo36 that could potentially have implications for jailbreaking if released.

Jailbreaking aside, firmware downgrades can also be useful for the vanilla iPhone and iPad community. If a particular firmware release introduces a bug, Apple’s narrow signing window presents a limited opportunity for users to downgrade to a more stable release that they’ve used previously. For this reason, it’s somewhat frustrating that Apple only provides approximately a week to downgrade one’s firmware if necessary.

As always, you can see which firmware versions are being signed for every one of Apple’s devices with the handy online utility.

Are you impacted in any way by Apple’s decision to stop signing iOS 13.5.1? Let us know in the comments section below.