Facebook CEO Mark Zuckerberg describes his company's latest scandal as a 'major breach of trust.'

Zuckerberg sat down with CNN's Laurie Segall in an exclusive interview to say he was "really sorry" for the data-sharing scandal involving Cambridge Analytica. Zuckerberg said Facebook 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 went on to describe the scandal as " probably the biggest mistake that we made here" and told Segall he was willing to testify before Congress. He went on to say that he was sure someone was trying to use Facebook to meddle in this year's midterm elections.

Back in 2014 Facebook made changes to its platform to limit the amount of data that could be obtained by third-party developers, but back in 2013, Aleksandr Kogan built a Facebook app that was allowed access to a broad range of data.

Even though he obtained the data legally, Facebook claims Kogan breached policy when he shared that information with a third party.

When Facebook learned about the information being shared, it asked Cambridge Analytica to destroy the data. Cambridge said it had.

Zuckerberg claims that's where Facebook went wrong. They took Cambridge at their word.

Still, the Facebook CEO says that Facebook plans to make this right by being open with users of the social media platform and informing everyone who may have been affected in the Cambridge breach.

Making mistakes is part of life and business, but Zuckerberg says this may be his worst. Let's see if he can make it right.