WinZip before 11.0 does not properly verify the authenticity of updates, which allows man-in-the-middle attackers to execute arbitrary code via a Trojan horse update, as demonstrated by evilgrade and DNS cache poisoning.
http://www.infobyte.com.ar/down/isr-evilgrade-1.0.0.tar.gz
http://www.infobyte.com.ar/down/Francisco%20Amato%20-%20evilgrade%20-%20ENG.pdf
http://securitytracker.com/id?1020581
http://archives.neohapsis.com/archives/bugtraq/2008-07/0250.html