Facebook Says Security Breach Affected Almost 50 Million Accounts

A picture taken in Paris on May 16 shows the logo of the social network Facebook on a broken screen of a mobile phone.

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Updated 5:37 p.m. ET

Facebook says that it has discovered a security breach affecting nearly 50 million accounts and that it’s not yet clear whether any information was accessed or any accounts were otherwise misused.

The vulnerability that caused the breach was found Tuesday and was fixed on Thursday night, Facebook says. It was the result of bugs introduced into Facebook’s code in July 2017. No passwords or credit card numbers were stolen, the company says.