This Situation was first highlighted by a Australian Blogger and hacker Nik Cubrilovic. Even following you are logged out, Facebook is in a position to track your browser’s web page every time you visit a site, only on websites that integrate with Facebook services like Facebook Like, Facebook Share, or Facebook Login.
In a statement he say,
“There was no security or privacy breach—Facebook did not shop or use any info it ought to not have. Like each and every internet site on the world wide web that personalises content material and tries to offer a secure experience for users, we place cookies on the personal computer of the user.
“Three of these cookies on some users’ computers inadvertently included distinctive identifiers when the user had logged out of Facebook. Even so, we did not shop these identifiers for logged out users. For that reason, we could not have employed this details for tracking or any other goal. In addition, we fixed the cookies so that they won’t contain distinctive details in the future when men and women log out.”
According to him he also informed Facebook about this concern on 14 November 2010 about this issue but he got no response until his post goes broadly on net. Now Facebook has stated that it has “fixed” cookies that could have tracked users after they logged out of the website. If you want to see the raw logs you can study them right here. So keep in mind to hold clearing your cookies
Study far more about it right here