CVE-2004-0978: Microsoft Internet Explorer

High severity, CVSS 10.0. EPSS: 38.3% chance of exploitation in the next 30 days.

Heap-based buffer overflow in the Hrtbeat.ocx (Heartbeat) ActiveX control for Internet Explorer 5.01 through 6, when users who visit online gaming sites that are associated with MSN, allows remote attackers to execute arbitrary code via the SetupData parameter.

Affected products

• Microsoft Internet Explorer: version 5.01 only; version 5.5 only; version 6 only

Published 2005-02-09. Last modified 2026-06-16.