Update: Facebook has shared more details about the bug, including that the flaw was live from May 18-27. Facebook’s Chief Privacy Officer also gave an updated statement.

In the latest installment of Facebook’s security and privacy issues, the company is letting up to 14 million users know if their posts were accidentally changed from private to public due to a bug last month.

Spotted by Recode, posts from up to 14 million Facebook users that had their content set to be shared privately was changed to be publicly seen. The software flaw was apparently live for 10 days last month and the company didn’t give users any kind of warning.

As Recode points out, the private/public setting on Facebook will be the same for new posts as it was on previous ones. So many users that keep posts set to private would have had no idea about the issue or may have not even thought to check the status.

Facebook hasn’t released specifics on the amount of users and posts involved other than it being up to 14 million. The company’s chief privacy officer shared a very brief statement, “We’d like to apologize for this mistake.”

You can see if you were affected by looking for a warning message in your Facebook notifications feed as seen below:

Here’s what the notification screen will look like for people who have been impacted by this bug pic.twitter.com/yaj1KMZTGr

— Kurt Wagner (@KurtWagner8) June 7, 2018