Facebook does NOT plan to notify half a billion users whose personal details were hacked before 2019 because 'it has no idea whose data was stolen' Facebook is blaming 'malicious actors' for hacking the personal details of more 530 million users prior to September 2019 CEO Mark Zuckerberg was among the hacking victims, whose details were published on a hackers forum last week The social media giant said it was uncertain of the identities of the half billion worldwide users who had been hacked, and would not be notifying them Facebook has said it has 'plugged the hole' that allowed hackers to steal the data