Matheus Mariano found a nasty High Sierra bug: the system dialog box to unlock an encrypted APFS container exposed the password for that container in the hint field.
As plaintext.
Whoops.
Mariano alerted Apple, and the company has replied with details on how to make sure your data is secure. According to Rene Ritchie, Apple is pushing a supplemental update to High Sierra to fix the dialog box and close the security issue, a little over a week since Mariano’s post went up.
It’s one to install as soon as it hits the Mac App Store today.