A design flaw in Avast Sandbox allows a potentially harmful program to escape the sandbox and infect the host by dropping its files out of it and/or by modifying existing legitimate files of any type. Affected products include Avast Internet Security v11.x.x, Avast Pro Antivirus v11.x.x, Avast Premier v11.x.x, Avast Free Antivirus v11.x.x, Avast Business Security v11.x.x, Avast Endpoint Protection v8.x.x, Avast Endpoint Protection Plus v8.x.x, Avast Endpoint Protection Suite v8.x.x, Avast Endpoint Protection Suite Plus v8.x.x, Avast File Server Security v8.x.x, and Avast Email Server Security v8.x.x.