The RichEdit component in Microsoft Windows 2000 SP4, XP SP2, and 2003 SP1; Office 2000 SP3, XP SP3, 2003 SP2, and Office 2004 for Mac; and Learning Essentials for Microsoft Office 1.0, 1.1, and 1.5 allows user-assisted remote attackers to execute arbitrary code via a malformed OLE object in an RTF file, which triggers memory corruption.