The passcode. This is all that’s left of iOS security in iOS 11. If the attacker has your iPhone and your passcode is compromised, you lose your data; your passwords to third-party online accounts; your Apple ID password (and obviously the second authentication factor is not a problem). Finally, you lose access to all other Apple devices that are registered with your Apple ID; they can be wiped or locked remotely. All that, and more, just because of one passcode and stripped-down security in iOS 11.
This has been a very bad week or two for Apple.