Facebook said Wednesday that Cambridge Analytica, a data firm with ties to President Donald Trump's campaign, may have had information on about 87 million Facebook users without the users' knowledge.
Facebook had previously said the number of people whose information may have been shared with Cambridge Analytica was only around 50 million. It announced the revised number in a blog post on Wednesday.
Facebook has said the data was initially collected by a professor for academic purposes in line with its rules. The information was later transferred to third parties, including Cambridge Analytica, in violation of Facebook's policies.
Starting next week, Facebook will tell people if their information was shared with Cambridge Analytica.
Facebook also said in the blog post Wednesday that "most people on Facebook" may have had their public profile information scraped by malicious actors. The people doing the scraping used account recovery and search tools that let users look people up by phone numbers and email addresses, then took information from profiles.
"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," said CTO Mike Schropfer in the post.
Facebook is turning off the search feature and changing how account recovery works. The post also outlines a number of other ways that Facebook is cracking down on third-party access to data.
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