Heap-based buffer overflow in Microsoft Outlook Express 6 and earlier, and Windows Mail for Vista, allows remote Network News Transfer Protocol (NNTP) servers to execute arbitrary code via long NNTP responses that trigger memory corruption.

Argument injection vulnerability involving Microsoft Outlook and Outlook Express, when certain URIs are registered, allows remote attackers to conduct cross-browser scripting attacks and execute arbitrary commands via shell metacharacters in an unspecified URI, which are inserted into the command line when invoking the handling process, a similar issue to CVE-2007-3670.

Microsoft Outlook 8.5 and earlier, and Outlook Express 5 and earlier, with the "Automatically put people I reply to in my address book" option enabled, do not notify the user when the "Reply-To" address is different than the "From" address, which could allow an untrusted remote attacker to spoof legitimate addresses and intercept email from the client that is intended for another user.

Microsoft Outlook client allows remote attackers to cause a denial of service by sending multiple email messages with the same X-UIDL headers, which causes Outlook to hang.

Microsoft Outlook Express before 4.72.3612.1700 allows a malicious user to send a message that contains a .., which can inadvertently cause Outlook to re-enter POP3 command mode and cause the POP3 session to hang.

Buffer overflow in the HTML library used by Internet Explorer, Outlook Express, and Windows Explorer via the res: local resource protocol.