Clam AntiVirus (ClamAV) 0.88.6 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.vupen.com/english/advisories/2006/5113
http://www.vupen.com/english/advisories/2006/4948
http://www.securityfocus.com/bid/21461
http://www.securityfocus.com/archive/1/453654/100/0/threaded
http://www.novell.com/linux/security/advisories/2006_78_clamav.html
http://www.mandriva.com/security/advisories?name=MDKSA-2006:230
http://www.debian.org/security/2006/dsa-1238
http://secunia.com/advisories/23460
http://secunia.com/advisories/23411
http://secunia.com/advisories/23379