The SMTP component in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, and Server 2008 Gold, SP2, and R2, and Exchange Server 2003 SP2, does not properly parse MX records, which allows remote DNS servers to cause a denial of service (service outage) via a crafted response to a DNS MX record query, aka "SMTP Server MX Record Vulnerability."