Facebook has apologized for a glitch that may have resulted in 14 million users having their private social posts shared publicly.<p>An error in its audience selector tool meant posts would automatically be flagged to share to the general public, which normally would remain set to whatever preferences the user ticked most recently, the company said on Thursday.<p>Facebook has started notifying the 14 million users affected by the glitch, which was active from 18 to 27 May this year.<p>Out of caution, the company has urged all users to review their posts during this time.