800,000 Facebook users blocked people who saw their posts anyhow

Facebook keeps making mistakes that share your info -- and this time it's with people you've explicitly blocked.

According to an official Facebook blog post, the company is notifying over 800,000 users that unwanted people may have seen posts on Facebook and Facebook Messenger, even if you'd proactively blocked those people from seeing your posts, between May 29 and June 5.

Mind you, they couldn't see private posts, or posts you'd only shared with your friends. But if you sent a post to "friends of friends" or a wider audience, blocked people could see them. And those people may have been able to contact people on Facebook Messenger who'd blocked them, potentially leading to harassment.