It seems that ensure the lock from the menu of emergency calls is has choking him several of the most important manufacturers of the Android platform, and after seeing multiple vulnerabilities in version 4.1.2 Jelly Bean from Samsung, now seems has managed to reproduce a similar on the same version of Android security but failure Sony firmware, that so far it is only available for the Xperia Z and T Xperia.
In the case of the Sony software, an attacker could bypass the blockade with any kind of security from the menu of emergency calls helping the development of Sony menu access, and thus take full control of the device without knowledge of the password or patterns.
Not knowing if the vulnerability is present in the original version of Android, the truth is that the custom firmware from Samsung and Sony have some security flaws that must be reviewed by both manufacturers.
In this case, perhaps the problem is more serious, because with the key combination that leads to the development of Sony menu we can run a simple test of the NFC chip and access a device that was perfectly blocked completely.
You can see it in the video shown below, and although Sony has not acted at the moment, it is likely that we will see an update soon to fix it: