Apple no longer signs iOS 12.3, 12.3.1 or 12.3.2 for its mobile device lineup as of Wednesday night, a move that prevents users from restoring to a firmware version older than iOS 12.4, released to the public only last year Monday.
It is not uncommon for Apple to stop signing older versions of iOS, especially a week or two after releasing a new update, but it is particularly noteworthy that Apple stopped signing at least three iterations of iOS in one. swoop this week, which doesn't happen too often.
The reason why Apple stops signing older versions of iOS is to promote software updates among the user base. To prevent downgrading of firmware, the company effectively ensures that users benefit from all the latest and greatest features and security updates. An unfortunate side effect of this scheme is that it makes recovery to jailbreakable versions of iOS more difficult, if not impossible.
Apple's decision to stop signing iOS 12.3-12.3.2 tonight doesn't particularly affect the jailbreak community since the latest jailbreakable version of iOS is 12.3 beta (which excludes iOS 12.3 public release). With that in mind, jailbreakers are already using earlier versions of iOS, and the only way current events could become a problem is if those same users needed to recover via iTunes for some reason.
If you are currently on iOS 12.3 – 12.3.2 and you are waiting for a jailbreak, then it is best to do where you are. However, given all the exploitation releases in recent memory, there is a high chance that these versions may become captivating in the future. While there is no guarantee of any stretches, the rule of thumb suggests that an exploit is more likely to be released for iOS 12.3-12.3.2 than for iOS 12.4.
For the record, there are legitimate reasons for non-jailbreakers to also downgrade the firmware to the iOS device, for example, if an update introduced a critical error of some kind. However, these cases are much less common.
As always, you can monitor the firmware signing status of some of your iOS devices with the IPSW.me electronic tool.
Has the closed signing window affected you in any way? Discuss in the comments section below.