A German security firm SRL claims a vulnerability in Touch ID Fingerprint Scanner and iCloud allows a hacker to access a locked device and potentially gain control over an owner’s Apple ID. Airplane mode can be enabled on a stolen phone from the lockscreen, which turns off wireless connectivity and so defeats the remote wipe facility. Since Find My iPhone can only perform a wipe if a device is connected to the Internet, that may give a thief enough time to get fingerprints off of the device and eventually log in.
Source: https://thehackernews.com/2013/10/iphone-fingerprint-scanner-hacked-again.html