The software problem automatically switched the privacy setting for new posts from private to public. Facebook has been criticized in recent months for sharing personal user data with third parties.
Scandal-hit social media giant Facebook apologized on Wednesday after it revealed that a software glitch had made some of its users' posts public for several days in May.
Facebook's chief privacy officer, Erin Egan, said the software changed the default privacy setting for new posts from private to public for some 14 million users between May 18 and May 27. The company identified the problem on May 22, but it took five days to reset the privacy setting for all of the affected posts.
The glitch occurred after Facebook introduced a new feature for users to share their photos and other content associated with their account.
"We'd like to apologize for this mistake," Egan said, adding that the company has been contacting affected users to tell them to review posts they published during that time.
Fraught times for Facebook
The glitch is the latest embarrassment for Facebook, the world's largest social media company with more than 2.2 billion global users.
Read more: Facebook posts profits despite data scandal
On Tuesday, the company admitted that Chinese phone maker Huawei was one of dozens of companies authorized to access vast amounts of user data. The confirmation raised eyebrows among US politicians, who cited the US government's fears that Huawei was closely affiliated with the China's ruling Communist Party.
In April, Facebook CEO Mark Zuckerberg apologized after it was revealed that Cambridge Analytica, a data consultancy, had improperly gained access to the data of up to 87 million Facebook users. Cambridge Analytica used some of the data to help US President Donald Trump's campaign team during the 2016 presidential election and the Vote Leave campaign during the 2016 Brexit referendum.
amp/bw (AP, dpa, AFP)