NATIONWIDE, (WOWO) – Facebook is alerting its users after a hacker was able to access 50 million people’s account information.

In a post Friday, Facebook Founder and CEO Mark Zuckerberg wrote the company discovered the attack Tuesday, stating the attacker stole access tokens that allowed them to log into about 50 million people’s accounts.

Zuckerberg continued the post, stating the company doesn’t know if the accessed accounts were misused in any way, and that Facebook is still investigating.

The issue involved the “View As” feature that allowed people to see their profile as other people would see it.

A number of steps have been taken to address the issue, such as patching the security vulnerability to prevent the attacker from stealing additional access tokens, temporarily taking down the feature that had the security vulnerability, and logging out anyone who used the “View As” feature since the vulnerability was introduced.