Researchers from the University of Regensburg, Germany, say Tor is vulnerable to fingerprinting attacks. Attackers could be able to analyze the patterns of data being returned through the Tor system. Tor is essentially an online mask, rather than a tool that hides the fact or content of communication itself. Users can guard against this type of fingerprint-based eavesdropping relatively easily, researchers say. The research many not dissuade many from using Tor, which remains one of the most promising approaches for individuals seeking to hide aspects of their identity or online activity.
Source: https://thehackernews.com/2010/12/privacy-flaw-found-in-tor-project.html