CVE-1999-1033: Microsoft Outlook Express

Medium severity, CVSS 5.0. EPSS: 17.5% chance of exploitation in the next 30 days.

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.

Affected products

• Microsoft Outlook Express: up to and including 4.72.3612.1700; version 4.27.3110.1 only; version 4.72.3120.0 only

Published 1999-05-11. Last modified 2026-06-16.