Facebook says 50M user accounts affected by security breach

NEW YORK -- Facebook says it recently discovered a security breach affecting nearly 50 million user accounts.

The company says hackers exploited the "View As" feature on the service. Facebook says it has taken steps to fix the security problem and alerted law enforcement.

Facebook said its engineering team found the security issue Tuesday afternoon, and took immediate action.

"Our investigation is still in its early stages. But it's clear that 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. Access tokens are the equivalent of digital keys that keep people logged in to Facebook so they don't need to re-enter their password every time they use the app," Facebook's statement said, in part.

The company has yet to determine if the accounts were misused, if any information was accessed or who is behind the breach.