Unspecified vulnerability in Symantec Norton AntiVirus 2005 through 2008; Norton Internet Security 2005 through 2008; AntiVirus Corporate Edition 9.0 before MR7, 10.0, 10.1 before MR8, and 10.2 before MR3; and Client Security 2.0 before MR7, 3.0, and 3.1 before MR8; when Internet Email Scanning is installed and enabled, allows remote attackers to cause a denial of service (CPU consumption and persistent connection loss) via unknown attack vectors.