Facebook Inc (NASDAQ:FB) has been blasted time and again for its privacy—or lack, thereof, in some ways—practices. Now it’s clear that not even the social network’s founder is immune to the holes in its privacy policies.

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A loophole in Facebook’s privacy settings

Most Facebook Inc (NASDAQ:FB) users think that when they set their friends list privacy to “Only Me,” it means that they are the only ones who can see it. However, anyone can take advantage of a loophole in the privacy. As Mashable reports, that loophole is the social network’s mutual friends feature.

All users can see mutual friends between any other two users if one of them has made their friends list publicly available. So, for example, if one user keeps her friends list private but her closest friend does not, then a third party could compare the two users’ lists to see all the friends they have in common.

Facebook isn’t worried

Facebook Inc (NASDAQ:FB) isn’t at all worried about this loophole and tells users that their privacy is really dependent upon the privacy settings of their friends. The social network began offering the mutual friends tool to help users find other people they know.

However, that tool could be a bigger problem than Facebook Inc (NASDAQ:FB) realizes. Cyberlnt put together a program that exploits that loophole and enables anyone to reconstruct anyone’s friends list—even if they have set it to private.

Building Mark Zuckerberg’s friends list

The website used Facebook Inc (NASDAQ:FB) founder and CEO Mark Zuckerberg’s friends list as an example. He has it set to private, although he is friends with Chris Cox, who heads up the social network’s products business. Cox’s list is set to public. The two Facebookers have 248 mutual friends, and using that number, along with comparing other friends’ lists for those connected with Zuckerberg and Cox, they were able to see over 400 names who have friended Zuckerberg on Facebook.

It should come as no surprise that Zuckerberg has friended most of the well-known technology icons in Silicon Valley, including fellow billionaires, venture capitalists, and CEOs. Of course he’s also friends with Marc Andreessen and Don Graham and some of Facebook Inc (NASDAQ:FB)’s earliest employees like Sean Parker, co-founder of Napster and former president of Facebook.

As Mashable reports, there were also some surprises on Zuckerberg’s list. For example, he friended Baidu Inc (ADR) (NASDAQ:BIDU) co-founder Robin Li, who is also the third wealthiest man in China. Other people who are on his friends list include Zynga Inc (NASDAQ:ZNGA) founder Mark Pincus’ wife Alison Pincus, Quora co-founder Charlie Cheever, Twitter Inc (NYSE:TWTR) co-founder Jack Dorsey, SurveyMonkey CEO Dav Goldberg and eBay Inc (NASDAQ:EBAY) President and CEO John Donahoe.