According to the article Warning: Your Browser Extensions Are Spying On You:
Browser add-ons for Chrome, Firefox, and probably other browsers are tracking every single page you visit and sending that data back to a third-party company that pays them for your information.
Millions of people are being tracked this way and they don’t have a clue.
The BBC recently wrote in the article It is easy to expose users' secret web habits, say researchers:
The information revealed an intimate portrait of the browsing habits of people, said Ms Eckert.
The pair found that 95% of the data they obtained came from 10 popular browser extensions.
How do I keep myself save in this regard? Is there some white list of friendly browser extensions? To take a specific example, how do I tell whether my uBlock extension is safe?