Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use malformed quoting in MIME headers, parameters, and values, including (1) fields that should not be quoted, (2) duplicate quotes, or (3) missing leading or trailing quote characters, which may be interpreted differently by mail clients.

Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use RFC2231 encoding, which may be interpreted differently by mail clients.

Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use whitespace in an unusual fashion, which may be interpreted differently by mail clients.

Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions via MIME messages that use fields that use RFC2047 encoding, which may be interpreted differently by mail clients.