The AntiVirus engine in the HTTP-ALG in Clavister CorePlus before 8.81.00 and 8.80.03 might allow remote attackers to bypass scanning via small files.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2007-3788
http://www.clavister.com/releasenotes/CorePlus_Release_Notes_8_81_01.pdf
http://www.clavister.com/releasenotes/CorePlus_Release_Notes_8_80_04.pdf