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.

MSHTML.DLL HTML parser in Internet Explorer 4.0, and other versions, allows remote attackers to cause a denial of service (application crash) via a script that creates and deletes an object that is associated with the browser window object.

Buffer overflow in VCard handler in Outlook 2000 and 98, and Outlook Express 5.x, allows an attacker to execute arbitrary commands via a malformed vCard birthday field.

Internet Explorer 5.0 and 5.5, and Outlook Express 5.0 and 5.5, allow remote attackers to execute scripts when Active Scripting is disabled by including the scripts in XML stylesheets (XSL) that are referenced using an IFRAME tag, possibly due to a vulnerability in Windows Scripting Host (WSH).

The Microsoft Outlook mail client identifies the physical path of the sender's machine within a winmail.dat attachment to Rich Text Format (RTF) files.

Microsoft Outlook 2000 does not properly process long or malformed fields in vCard (.vcf) files, which allows attackers to cause a denial of service.

Microsoft Outlook 98 and 2000, and Outlook Express 4.0x and 5.0x, allow remote attackers to read files on the client's system via a malformed HTML message that stores files outside of the cache, aka the "Cache Bypass" vulnerability.

Microsoft Outlook Express allows remote attackers to monitor a user's email by creating a persistent browser link to the Outlook Express windows, aka the "Persistent Mail-Browser Link" vulnerability.

Buffer overflow in Microsoft Outlook and Outlook Express allows remote attackers to execute arbitrary commands via a long Date field in an email header, aka the "Malformed E-mail Header" vulnerability.

Microsoft Outlook and Outlook Express allow remote attackers to cause a denial of service by sending email messages with blank fields such as BCC, Reply-To, Return-Path, or From.