The MimeOleClearDirtyTree function in InetComm.dll in Microsoft Outlook Express 6.00.2900.5512 does not properly handle (1) multipart/mixed e-mail messages with many MIME parts and possibly (2) e-mail messages with many "Content-type: message/rfc822;" headers, which allows remote attackers to cause a denial of service (infinite loop) via a large e-mail message, a related issue to CVE-2006-1173.