Samsung phones have been notorious to have bypass methods for their lockscreens, specifically in the last month or so. There is yet another bypass, which allows access to the device on a PIN-secured screen by unauthorized users. There is a combination of key presses and commands to perform this exploit.
These certain circumstances are rather specific in order to apply this exploit, which allows brief access to the homescreen after a failed emergency call is placed for the lockscreen. Terrence Eden discovered this along with many other exploits on these devices. There is only brief and limited access allowed with this however. If you were to have this device for a long enough time you could download apps, read SMS, or place calls.
There has been a patch promised from Samsung to fix this in the near future, but there is no worry as Eden has decided not to post details until the patch has been issued.