"Our security systems have detected that a lot of people are posting the same content, which could mean that it's spam," a message told users. Facebook later apologised for the misfire. Facebook has suffered narrower breaches before. In 2013, Facebook disclosed a software flaw that exposed 6 million users' phone numbers and email addresses to unauthorized viewers for a year, while a technical glitch in 2008 revealed confidential birth-dates on 80 million Facebook users' profiles. US lawmakers said on Friday that the hack may boost calls for data privacy legislation. "This is another sobering indicator that Congress needs to step up and take action to protect the privacy and security of social media users," Democratic U.S. Senator Mark Warner said in a statement.