Avast Free Antivirus Link Following Denial-of-Service Vulnerability. This vulnerability allows local attackers to create a denial-of-service condition on affected installations of Avast Free Antivirus. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the Avast Service. By creating a symbolic link, an attacker can abuse the service to create a folder. An attacker can leverage this vulnerability to create a denial-of-service condition on the system. Was ZDI-CAN-22806.