Facebook says a bug in its system led 6 million users' contact information to be inadvertently exposed.
The social media company said Friday that a bug led to some contact information - such as email addresses or phone numbers - to be uploaded by other users.
The problem arose when Facebook users downloaded an archive of their Facebook account through Facebook's "Download Your Information" tool. Because of the bug, users may have been provided with additional email addresses or telephone numbers for their contacts or people with whom they have some connection.
Because the contact information was provided by other people on Facebook, it was not necessarily accurate.
Facebook says it has fixed the problem and is in the process of notifying affected users via email.