It looks like the Sony Xperia Z (C660X) is the latest in a long line of smartphones to see its lock screen bypassed, posing a big security risk if your phone falls into the wrong hands. The bypass is easy to do and involves hitting the ‘Emergency call’ button when the lock screen appears. You then need to enter the appropriate codes (*#*#7378423#*#*) to enter the service menu, the same on all Xperia phones.
Once inside, click on Service tests > NFC > NFC Diag Test and then hit the home button. You can now browse the phone as normal. We have just tested this on our resident Xperia Z and can confirm the above works without any problems. The lock screen can’t be changed without knowing the passcode or pattern, but you can access all areas of the phone. Let’s hope Sony fixes this exploit as soon as possible.