Apple has yet to fix the first bug found in iOS 7 which allows anyone to bypass the lockscreen and access photos, emails, Twitter, and more. Apple is aware of this bug and says a fix will come in a future iOS update.
An iPhone user named Karam Daoud discovered that you can dial any number from the Emergency call page of a lockscreen. If you press the green phone button multiple times after you enter the number, the screen turns black with an Apple logo, and the call will go through.
Many have tested this lockscreen bug, some were successful in recreating it, but some experienced inconsistent results.
We will inform you if Apple releases any official statement.