A zero-day exploit in the wild has been used by threat actors to de-anonymize Tor users by executing malicious code on Windows machines. The vulnerability was first mentioned on the official Tor website, a blog post quoted a Javascript exploit that is actively exploited in the the wild to unmask Tor Browser users. The security researcher Raylee (@TheWack0lian) explained that the payload used in the recent wave of attacks is quite similar to the one used by law enforcement in 2013.”]
Source: https://securityaffairs.co/wordpress/53922/hacking/firefox-zero-day-exploit.html