ClamAV 0.80 and earlier allows remote attackers to bypass virus scanning via a base64 encoded image in a data: (RFC 2397) URL.
http://www.mandriva.com/security/advisories?name=MDKSA-2005:025
http://www.gentoo.org/security/en/glsa/glsa-200501-46.xml
http://sourceforge.net/project/shownotes.php?release_id=300116
http://secunia.com/advisories/13900/