CEO Mark Zuckerberg addressed the issue in a post on Friday.
Facebook says they have discovered a breach in their online security system which had the potential to allow hackers to appropriate over 50 million accounts.
"Since we’ve only just started our investigation, we have yet to determine whether these accounts were misused or any information accessed. We also don’t know who’s behind these attacks or where they’re based," Facebook vice president of product management Guy Rosen said in a blog post Friday.
The discovery was made on Tuesday which allowed the criminals to sign in using "access tokens" and control people's personal information. There is still no word on whether or not the thieves misused that ability.
Law enforcement was notified according to NBC 7.
The social media giant says 90 million people will have to mandatorily sign into Facebook after which a message will appear telling them of the compromise.
The company saw its market shares drop as a result of the news, CEO Mark Zuckerberg updated the public on his page Friday.
"While I'm glad we found this, fixed the vulnerability, and secured the accounts that may be at risk, the reality is we need to continue developing new tools to prevent this from happening in the first place," he wrote.
No information was given about which part of the world was most affected by the breach.
The attorney general of North Carolina, Josh Stein, suggested in a Twitter post that his office would investigate the breach.