The LDAP server in Active Directory in Microsoft Windows 2000 SP4 and Server 2003 SP1 and SP2 responds differently to a failed bind attempt depending on whether the user account exists and is permitted to login, which allows remote attackers to enumerate valid usernames via a series of LDAP bind requests, as demonstrated by ldapuserenum.

Microsoft Windows XP SP2 and SP3, and Server 2003 SP1 and SP2, does not properly validate the option length field in Pragmatic General Multicast (PGM) packets, which allows remote attackers to cause a denial of service (infinite loop and system hang) via a crafted PGM packet, aka the "PGM Invalid Length Vulnerability."