Web bug reveals browsing history

Porn sites are among the top users of a browser bug that reveals all the places people go online, finds research.Carried out by computer science researchers at UC San Diego the study found 485 sites exploiting the bug.The flaw gives sites access to all the other sites that user has visited. Many use it to target ads or see if users are patronising rivals.
http://www.bbc.co.uk/news/technology-11899092