A few days ago I was logged out of Facebook on all of my devices. Problem which has happened not only to me seems to be insignificant, but its cause is not trivial. Mark Zuckerberg on his official account reported that Facebook fell victim to a hacker attack five days ago, and logging out of accounts is the result of this attack.
Zuckerberg said that up to 50 million accounts on the portal could have been hacked. However, this does not mean that if you have been logged out from website then your account is at risk because, as reported by Facebook's co-founder, over 90 million of accounts have been logged out so data of around 40 million of people are safe. The problem has already been fixed, but it's unknown what data has been copied from Facebook's servers. We also don't know who was responsible for this attack, but Facebook is investigating this matter. If you want to keep track of reports regarding this problem, we recommend following the official account of Mark Zuckerberg. In addition, for full security, we recommend also changing the password on Facebook if you have an account on this website.