Facebook said today that it was informing 14 million users that they may have accidentally shared posts publicly because of a bug.

The company disclosed today that the bug, which was live last month, switched the “suggested” sharing setting on some users’ posts to the “public” setting. Facebook generally sets its suggestions for sharing based on users’ settings and previous activity. But in this case, a software error caused the default setting to be set to public, regardless of whether users had previously chosen to share with a smaller group of people.

Facebook said the bug was active between May 18th and May 27th, and although the company was able to stop the error on May 22nd, they could not revert posts to previous settings until five days later. The company is sending a notification to the 14 million users affected, and it has set their posts to the previously suggested settings.

The disclosure is the latest in a string of major privacy blunders that have followed Facebook since the Cambridge Analytica scandal. Before the announcement, the company was fending off questions from the public and lawmakers this week about how it shares data with device makers.

“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,” Facebook chief privacy officer Erin Egan said in a statement. “To be clear, this bug did not impact anything people had posted before — and they could still choose their audience just as they always have. We’d like to apologize for this mistake.”