Kaspersky Anti-Virus for Linux Mail Servers 5.5.10 allows remote attackers to bypass virus detection by inserting invalid characters into base64 encoded content in a multipart/mixed MIME file, as demonstrated with the EICAR test file.
http://www.securityfocus.com/bid/21461
http://www.securityfocus.com/archive/1/453654/100/0/threaded