Microsoft Outlook Express 6.0 and Outlook 2000, with the security zone set to Internet Zone, allows remote attackers to execute arbitrary programs via an HTML email with the CODEBASE parameter set to the program, a vulnerability similar to CAN-2002-0077.

The IMAP Client for Outlook Express 6.00.2800.1106 allows remote malicious IMAP servers to cause a denial of service (crash) via certain large literal size values that cause either integer signedness errors or integer overflow errors.

The IMAP Client for Sylpheed 0.8.11 allows remote malicious IMAP servers to cause a denial of service (crash) via certain large literal size values that cause either integer signedness errors or integer overflow errors.

Outlook Express 6.0 does not delete messages from dbx files, even when a user empties the Deleted items folder, which allows local users to read other users email.

Buffer overflow in Microsoft Outlook Express 5.0, 5.5, and 6.0 allows remote attackers to cause a denial of service (crash) via a long <A HREF> link.

Buffer overflow in the S/MIME Parsing capability in Microsoft Outlook Express 5.5 and 6.0 allows remote attackers to execute arbitrary code via a digitally signed email with a long "From" address, which triggers the overflow when the user views or previews the message.

The (1) CertGetCertificateChain, (2) CertVerifyCertificateChainPolicy, and (3) WinVerifyTrust APIs within the CryptoAPI for Microsoft products including Microsoft Windows 98 through XP, Office for Mac, Internet Explorer for Mac, and Outlook Express for Mac, do not properly verify the Basic Constraints of intermediate CA-signed X.509 certificates, which allows remote attackers to spoof the certificates of trusted sites via a man-in-the-middle attack for SSL sessions, as originally reported for Internet Explorer and IIS.

Outlook Express 5.5 and 6.0 on Windows treats a carriage return ("CR") in a message header as if it were a valid carriage return/line feed combination (CR/LF), which could allow remote attackers to bypass virus protection and or other filtering mechanisms via a mail message with headers that only contain the CR, which causes Outlook to create separate headers.

Buffer overflow in various Microsoft applications for Macintosh allows remote attackers to cause a denial of service (crash) or execute arbitrary code by invoking the file:// directive with a large number of / characters, which affects Internet Explorer 5.1, Outlook Express 5.0 through 5.0.2, Entourage v. X and 2001, PowerPoint v. X, 2001, and 98, and Excel v. X and 2001 for Macintosh.

Outlook Express 6.0, with "Do not allow attachments to be saved or opened that could potentially be a virus" enabled, does not block email attachments from forwarded messages, which could allow remote attackers to execute arbitrary code.