CVE-2004-1109: Kerio Personal Firewall

Medium severity, CVSS 5.0. EPSS: 3.2% chance of exploitation in the next 30 days.

The FWDRV.SYS driver in Kerio Personal Firewall 4.1.1 and earlier allows remote attackers to cause a denial of service (CPU consumption and system freeze from infinite loop) via a (1) TCP, (2) UDP, or (3) ICMP packet with a zero length IP Option field.

Affected products

• Kerio Personal Firewall: version 4.0.6 only; version 4.0.7 only; version 4.0.8 only; version 4.0.9 only; version 4.0.10 only; version 4.0.16 only; …

Published 2005-01-10. Last modified 2026-06-16.