Some 50 million accounts impacted in Facebook security breach.

Facebook is responding to a security breach that gave hackers access to information that could have allowed them to take over some 50 million accounts.

According to CNBC Online, the weakness was in Facebook’s code for its View As feature and was noticed on Tuesday after it saw increased activity on Sept. 16. Hackers were also able to access tokens or digital keys that allow users to remain logged in, that could be used to control accounts. Facebook has reset the tokens for the 50 million accounts, as well as for another 40 million accounts that used the View As feature in the past year as a precaution.

Impacted users will need to re-enter their password when they return to Facebook.