Two independent research teams have found out that hackers misused new CSS standards to steal pictures and data from Facebook. They specifically targetted users using Chrome and Firefox.
Hackers used something called "mix-blend-mode" in CSS to read information about images and even read text using optical character readers. The vulnerability has now been patched but one of the researchers, Dario Weißer, warns that there might be similar attacks in future.
These things can steal your data , so be carefull