Mark Zuckerberg Interview on The Facebook Accounts Scandal

I'm really sorry." With that apology, Mark Zuckerberg's trying to fix the damage done to Facebook in the data-sharing scandal with Cambridge Analytica. Zuckerberg, in an exclusive interview with CNN's Laurie Segall, said the social media site was changing its policies to make sure user data is protected after Cambridge Analytica -- which had ties to Donald Trump's 2016 campaign -- grabbed info from 50 million Facebook users without their knowledge.

He called the scandal "probably the biggest mistake that we made here"; said he's willing to testify about this before Congress, "if it's the right thing to do"; and admitted he's sure "someone's trying" to use Facebook to meddle in this year's midterm elections. CNN's Chris Cillizza says Facebook's problems are so bad, not even a techno wizard like Zuckerberg may be able to solve them.