IBUS < 1.5.4 - Unauthenticated Password Exposure via Lockscreen Display
The default configuration of IBUS 1.5.4, and possibly 1.5.2 and earlier, when IBus.InputPurpose.PASSWORD is not set and used with GNOME 3, does not obscure the entered password characters, which allows physically proximate attackers to obtain a user password by reading the lockscreen.