This article describes that researchers have found a critical vulnerability that users could leak their real IP addresses to potential attackers when they use TOR anonymity browser. Tor (The Onion Router) is free software for enabling anonymous communication and was initially a worldwide network of servers developed with the U.S Navy that enabled people to browse the internet anonymously. Now it’s a non-profit organization whose main purpose it the research and development of online privacy tools. According to the article, the security researcher Filippo Cavallarin mentions that the vulnerability resides in FireFox that eventually affects Tor Browser since the privacy-aware service that allows users to surf the web anonymously uses FireFox at its core. The security researcher also describes that the vulnerability currently only effect for MacOS and Linux users only. However, the research warning Tor users to be aware of this vulnerability.