The exploit, demonstrated by YouTube user EverythingApplePro yesterday, was never really of any concern to iPhone users because of the extreme parameters required to make it work in a timely manner, according to TechCrunch. It uses a $500 piece of hardware, requires physical access to an iPhone 7 or 7 Plus, realistically only works with a 4 digit passcode, and slows down drastically more than 10 minutes after an iPhone's passcode was last changed.
The "box" shown off in the video is similar to tools used by law enforcement officials, and while passcode-guessing hardware like this does not normally work at this speed because iOS devices lock you out after several failed passcode entry attempts, there is a bug in iOS 10 that makes it possible to guess a passcode over and over for a short period directly after the passcode has been changed. TechCrunch explains:
On iOS 10, there is a "bug" for lack of a better term, that allows repeated, rapid guesses of the passcode if you've changed it within the last minute or so. This allows the box to work within that period. Once another threshold is crossed -- say 10 minutes after a passcode is changed -- you no longer have the freedom to guess rapidly.Without the rapid guessing enabled by the iOS 10 bug, it takes much, much longer for a solution like box to get into an iPhone because it's slowed down by Apple's passcode timeout. A six digit passcode (now the default on iOS devices) that had not been changed recently would take approximately 9.5 years to crack, for example.
According to Apple, the behavior that allows the box to work has been patched as of iOS 11 beta 4.