The lockscreen on Elephone P9000 devices (running Android 6.0) allows physically proximate attackers to bypass a wrong-PIN lockout feature by pressing backspace after each PIN guess.
https://www.youtube.com/watch?v=dwyzonP2eZw
https://www.trustwave.com/Resources/Security-Advisories/Advisories/TWSL2017-011/?fid=9707
https://www.security.nl/posting/522081/Schermvergrendeling+Elephone+P9000+door+lek+te+omzeilen
https://www.reddit.com/r/netsec/comments/6kajkc/elephone_p9000_lock_screen_lockout_bypass_with/