"The bug, which has since been repaired, was part of the Download Your Information tool, which lets Facebook users export all the data from profiles, such as posts to their timeline and conversations with friends. People using the tool may have downloaded inadvertently the contact information for people they were somehow connected to."
Facebook adds that the addresses or numbers were only shared with one person "in almost all cases," and that the information was only accessible to people on Facebook — not to developers or advertisers.
"It's still something we're upset and embarrassed by, and we'll work doubly hard to make sure nothing like this happens again," the company says.
