How i can protect my android from Master Key Vulneralability?
You can check whether your device is affected using e.g. Bluebox Security Scanner.

To close the vulnerability, your device needs root access. If that pre-condition is given, there are different fixes available, e.g.


Master Key dual fix (a module for the xposed-framework)
Master-Key Security Patch (again a module for Xposed)
ReKey (a stand-alone app)