Facebook hacked on Friday and digital login codes stolen allowing attackers to take over nearly 50 million user accounts.
It in its worst security breach ever given the unprecedented level of potential access, adding to what has been a difficult year for the company’s reputation.
Facebook, which has more than 2.2 billion monthly users, said it has yet to determine whether the attacker misused any accounts or stole private information.
It also has not identified the attacker’s location or whether specific victims were targeted. Its initial review suggests the attack was broad in nature.
Chief Executive Mark Zuckerberg described the incident as “really serious” in a conference call with reporters.
His account was affected along with that of Chief Operating Officer Sheryl Sandberg, a spokeswoman said.
Shares in Facebook fell 2.6 percent on Friday, weighing on major Wall Street stock indexes.
Facebook made headlines earlier this year after profile details from 87 million users was improperly accessed by political data firm Cambridge Analytica.
The disclosure has prompted government inquiries into the company’s privacy practices across the world, and fueled a “#deleteFacebook” social movement among consumers.
U.S. 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.
Federal Trade Commission Commissioner Rohit Chopra on Twitter said “I want answers” with a link to a Reuters story on the breach.
