Microsoft Internet Explorer 5.01 SP4 and 6 SP1; Internet Explorer 6 for Windows XP SP2 and SP3 and Server 2003 SP2; and Internet Explorer 7 and 8 for Windows XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1, and SP2, and Server 2008 Gold and SP2 do not properly handle attempts to access deleted objects in memory, which allows remote attackers to execute arbitrary code via an HTML document containing embedded style sheets that modify unspecified rule properties that cause the behavior element to be "improperly processed," aka "Uninitialized Memory Corruption Vulnerability."