Facebook CEO Mark Zuckerberg says Cambridge Analytica gathered info on up to 87 million Facebook accounts

The world's most influential social-media company has acknowledged that it didn't do enough to protect users' privacy.

Facebook CEO Mark Zuckerberg told reporters today that an app used by Cambridge Analytica researcher Alexandr Kogan gained access to up to 87 million accounts.

Of those, about 622,000 were in Canada—or about 0.7 percent. More than 80 percent were in America.

U.K.-based Cambridge Analytica turned data over to the Donald Trump presidential campaign and to those campaigning to pull Britain out of the European Union.

"Just to give you the complete picture on this: we don’t have logs going back from when exactly Kogan’s app queried for everyone’s friends," Zuckerberg said. "What we did was basically constructed the maximum possible number of friends lists that everyone could have had over the time, and assumed that Kogan queried each person at the time when they had the maximum number of connections that would’ve been available to them.

"That’s where we came up with this 87 million number," the Facebook CEO continued. "We wanted to take a broad view that is a conservative estimate. I am quite confident that given our analysis that it is not more than 87 million. It very well could be less, but we wanted to put out the maximum we felt that it could be as that analysis says."

Zuckerberg will testify before two U.S. Congressional hearings next week.

The U.K. information commissioner, Canada's privacy commissioner, and British Columbia's information and privacy commissioner have all launched investigations in connection with the Cambridge Analytica scandal. 

"The reality of a lot of this is that when you are building something like Facebook that is unprecedented in the world, there are going to be things that you mess up," Zuckerberg said. "And if we had gotten this right, we would have messed something else up.

"I don’t think anyone is going to be perfect, but I think what people should hold us accountable for is learning from the mistakes and continually doing better and continuing to evolve what our view of our responsibility is — and, at the end of the day, whether we’re building things that people like and that make their lives better."

In a post on Facebook's website, chief technology officer Mike Schroepfer outlined several changes, including new restrictions on searches, to enhance privacy.

He stated that "malicious actors" have abused the search function by inserting email addresses and/or phone numbers to scrape profile information.

"Given the scale and sophistication of the activity we’ve seen, we believe most people on Facebook could have had their public profile scraped in this way," Schroepfer stated. "So we have now disabled this feature. We’re also making changes to account recovery to reduce the risk of scraping as well."