The social media giant Facebook has revealed a new bug that switched 14 million users' privacy settings to public without their permission.
Affected users had the privacy settings of their posts automatically set to be shared to "everyone", even if they had chosen a setting which restricted who could see them.
The bug affected Facebook's internal systems between 18 and 22 May; the social media company was not able to return the posts to their original settings until 27 May.
It occurred when Facebook was testing a new feature and meant that it accidentally changed a user's privacy settings to public from whatever it was previously, making potentially sensitive status updates viewable from anywhere in the world.
Facebook said users who were affected by the bug will be notified of the issue on their news feed.
"We have fixed this issue and starting today we are letting everyone affected know and asking them to review any posts they made during that time," said Erin Egan, Facebook's chief privacy officer, adding: "We'd like to apologise for this mistake."