Unspecified vulnerability in Microsoft Word allows user-assisted remote attackers to execute arbitrary code on Word 2000, and cause a denial of service on Word 2003, via unknown attack vectors that trigger memory corruption, as exploited by Trojan.Mdropper.W and later by Trojan.Mdropper.X, a different issue than CVE-2006-6456, CVE-2006-5994, and CVE-2006-6561.