CVE-2002-1831: Microsoft Msn Messenger

Medium severity, CVSS 5.0. EPSS: 22.3% chance of exploitation in the next 30 days.

Microsoft MSN Messenger Service 1.0 through 4.6 allows remote attackers to cause a denial of service (crash) via an invite request that contains hex-encoded spaces (%20) in the Invitation-Cookie field.

Affected products

• Microsoft Msn Messenger: version 1.0 only; version 2.0 only; version 2.2 only; version 3.0 only; version 3.6 only; version 4.0 only; …

Published 2002-12-31. Last modified 2026-06-16.