The bug was first discovered in March when Belgian researchers reported that Facebook was tracking users across pages with its plugins - despite the users opting into a do-not-track system or not even being on the site.
Facebook denied the reports at the time, but this week it published a press release aimed at "Setting the Record Straight on a Belgian Academic Report." It addressed the academic report that came out of the University of Leuven and Vrije Universiteit Brussels.
"The researchers did find a bug that may have sent cookies to some people when they weren't on Facebook. This was not our intention - a fix for this is already under way," Allan wrote.
"We deliberately chose to open up our findings to public scrutiny so that anyone can check our sources and methodology. People who are interested can compare the 'claims' Facebook attributes to our report with its actual contents."
Facebook did not say when the bug fix would be implemented.
