The Facebook CEO ducked questions on how Facebook tracks even those internet users who are not logged in the social media site.
During the live-streamed hearing on Capitol Hill, the Democratic senator asked Zuckerberg whether he'd be comfortable sharing the name of the hotel he'd stayed in the night before.
Facebook was sued Tuesday in a class-action lawsuit in federal court, alleging the social media company failed to protect the personal information of 70.6 million users in the USA and over one million in the United Kingdom.
After the exchange, Senator Kennedy went on to say Facebook's "user agreement sucks" and that him and Zuckerberg were "not connecting".
Critics blamed Facebook for the spread of misinformation during the election, and Russian agents also used fake social media accounts to share divisive content in the U.S.
The five-hour hearing saw senators launch questions ranging from censorship, freedom of speech and hate speech, consumer privacy to election interference.
It came as Zuckerberg admitted his slow reaction to Russian meddling in the United States election was "one of my greatest regrets" in a blockbuster Senate hearing. Bill Nelson (D-FL.) raised the possibility of legislative regulation to curb data hacking, telling Zuckerberg that "if Facebook and other online companies will not or can not fix these privacy invasions, then we will". Cambridge Analytica is one example of how a malicious actor used Facebook's third-party data consent to sweep up tens of millions of records, but experts agree that it's not going to be the only case that comes to light.
"In retrospect, that was clearly a mistake".
"There are people in Russian Federation whose job it is to try to exploit our systems and other internet systems and other systems as well". Mark said, "I believe deeply in what we are doing and I know that when we address these challenges, we'll look back and view helping people connect and giving more people a voice as a positive force in the world. We need to invest in getting better at this too." he said.
While not everyone has received the notification yet, Facebook's help center now has a section that tells users whether they or their friend (s) were affected.