Apparently PC Pro likes to be late to the game. They are reporting that modern smart phones are vulnerable to “smudge attacks.” So what is a “smudge attack?” It’s a fancy term for saying you can look at the finger prints on the touchscreen of a phone to determine the password or unlock pattern for the phone.
Of course the simple and free solution; just wipe your phone’s screen off on your shirt periodically. Hell I do this naturally already because the finger prints make the screen hard to read.