CVE-2009-4171: Yahoo Messenger

Medium severity, CVSS 4.3. EPSS: 5.1% chance of exploitation in the next 30 days.

An ActiveX control in YahooBridgeLib.dll for Yahoo! Messenger 9.0.0.2162, and possibly other 9.0 versions, allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) by calling the RegisterMe method with a long argument.

Affected products

• Yahoo Messenger: version 9.0.0.2162 only

Published 2009-12-02. Last modified 2026-06-16.