McAfee GroupShield for Microsoft Exchange on Exchange Server 2000, and possibly other anti-virus or anti-spam products from McAfee or other vendors, does not scan X- headers for malicious content, which allows remote attackers to bypass virus detection via a crafted message, as demonstrated by a message with an X-Testing header and no message body.

The Network News Transfer Protocol (NNTP) component of Microsoft Windows NT Server 4.0, Windows 2000 Server, Windows Server 2003, Exchange 2000 Server, and Exchange Server 2003 allows remote attackers to execute arbitrary code via XPAT patterns, possibly related to improper length validation and an "unchecked buffer," leading to off-by-one and heap-based buffer overflows.