A vulnerability in Kaspersky Antivirus software had exposed a unique identifier associated with users to every website they have visited in the past 4 years. The exposure of this identifier allowed visited websites and commercial third-party services to track users online. The vulnerability was discovered by the security researcher Ronald Eikenberg, it resides in the URL scanning module of the antivirus software. The string could be easily used by websites, advertising, and analytics services to tracking users online. The same ID was permanently associated with each system running the software.”]
Source: https://securityaffairs.co/wordpress/89917/hacking/kaspersky-antivirus-flaw.html