This can be very dangerous but however, you can fix this bug using a few solutions.
- If you're using the CyanogenMod ROM, stay calm - this ROM has already the patch.
- If not, get the Bluebox Security Scanner and scan for malicious apps.
- Uncheck Apps from unknown sources option in Settings->Security
- [ROOT] Download ReKey app and install the patch.
- [ROOT] Or, If you're using the Xposed Installer, download THIS app and allow the module in Xposed Installer in Modules section. Then reboot. (I recommend this option because the BlueBox Sec. Scanner reports as UnPatched using the ReKey app.)