Facebook announced on Friday that a massive security breach was discovered on September 25th and has affected over 50 million accounts. The company has since fixed the vulnerability and contacted law enforcement.

This newest breach comes just six months after news broke that Cambridge Analytica had syphoned and retained the data of 50 million users. The implications of this breach included the data being used to influence the 2016 presidential election. Unlike the Cambridge Analytica scandal which saw a third-party company retaining data, this latest breach saw attackers able to directly take over Facebook user accounts.

The statement explains the breach was linked to the “View As” feature on the site which allows users to see their profile as it looks like to other users; “attackers exploited a vulnerability in Facebook’s code that impacted “View As” a feature that lets people see what their own profile looks like to someone else. This allowed them to steal Facebook access tokens which they could then use to take over people’s accounts.”

Users whose accounts were affected will have to log back in to their accounts on all platforms and there’ll be a post at the top of their newsfeed explaining the hack. The prompt reads “”Your privacy and security are important to us, we want to let you know about recent action we’ve taken to secure your account,” followed by a link to find out more.

This latest breach rounds out a pretty rough couple of years for Facebook, who are currently testing their “Dating” feature, watch the unveiling below.

You can check where your account has been logged in to here, and manually log them out.

Watch: Mark Zuckerberg announces “Dating”