The DNS implementation in smtpsvc.dll before 6.0.2600.5949 in Microsoft Windows 2000 SP4 and earlier, Windows XP SP3 and earlier, Windows Server 2003 SP2 and earlier, Windows Server 2008 SP2 and earlier, Windows Server 2008 R2, Exchange Server 2003 SP3 and earlier, Exchange Server 2007 SP2 and earlier, and Exchange Server 2010 does not verify that transaction IDs of responses match transaction IDs of queries, which makes it easier for man-in-the-middle attackers to spoof DNS responses, a different vulnerability than CVE-2010-0024 and CVE-2010-0025.