This is not a hoax. Many are unaware of this but Guy Rosen, VP of Product Management published in Facebook’s Newsroom that:
“On the afternoon of Tuesday, September 25, our engineering team discovered a security issue affecting almost 50 million accounts. We’re taking this incredibly seriously and wanted to let everyone know what’s happened and the immediate action we’ve taken to protect people’s security.”
According to FB, the presumed cause of the flaw was FB’s “view as” feature. This allows FB users to view what other people see in their own profiles.
As of this moment, Facebook disclosed that it had fixed this vulnerability, but is still investigating if there were accounts that were used maliciously. FB also revealed that they have contacted concerned authorities about the matter.
They ensure that they have taken immediate action and that users don’t need to change their passwords. If you have trouble logging into Facebook, you should visit Facebook’s “Help Center”, or you can visit “Security and Login”, if you want to be more cautious.
So, don’t access “view as” and follow the instructions above.