A bug in Facebook may have caused 14 million users to unknowingly post publicly, even if they specified restrictive defaults in their settings, Recode reported.
The bug was active from 18-22 May 2018 and updated the default audience for posts from certain users to public without any warning.
It took Facebook until 27 May to discover and fix the issue, and switch posts back to their default audience.
Facebook said the users who were affected will be notified in their Newsfeed.
The company said the bug did not impact old posts, and a user could set their audience if they spotted that the default had changed.
“We’d like to apologise for this mistake,” said Facebook.