CVE-2004-1109: The FWDRV.SYS driver in Kerio Personal Firewall 4.1.1 and earlier allows remote attackers to cause a denial of

This month

MEDIUM 5.0DOWNGRADE

CVE-2004-1109 is a medium-severity flaw (CVSS 5.0) affecting personal firewall. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	3.2% (top 12%)
CISA exploited list	No
Published	2005-01-10
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: kerio

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2005-01-10 05:00 UTCPublished CVE record published
2026-06-16 22:07 UTCUpdated Record last modified

kerio personal firewall DOWNGRADE

Affected: 4.0.6 · 4.0.7 · 4.0.8 · 4.0.9 · 4.0.10 · 4.0.16 · 4.1 · 4.1.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0.6

1. Check installed version

apt-cache policy personal-firewall || rpm -q personal-firewall || personal-firewall --version

2. No fixed release: DOWNGRADE to a release before 4.0.6 (Debian / Ubuntu)

apt-cache madison personal-firewall sudo apt install personal-firewall=<VERSION_BEFORE_4.0.6> sudo apt-mark hold personal-firewall

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list personal-firewall sudo dnf downgrade personal-firewall-<VERSION_BEFORE_4.0.6> sudo dnf versionlock add personal-firewall

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Kerio Personal Firewall 4.1.1 - Multiple IP Options Denial of Service Vulnerabilities

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2004-1109?

personal firewall: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2004-1109 being exploited?

CVE-2004-1109 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2004-1109 affect?

CVE-2004-1109 affects personal firewall. Severity is medium (CVSS 5.0). 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 O

How urgent is CVE-2004-1109?

Priority 45/100. Public exploit reference

Related CVEs

CVE-2009-2450 HIGH 7.2 UPGRADE UPGRADE The OAmon.sys kernel driver 3.1.0.0 and earlier in Tall Emu Online Armor Personal Firewall AV+ before 3.5.0.12
CVE-2008-3174 MEDIUM 5.0 DOWNGRADE DOWNGRADE Unspecified vulnerability in the kmxfw.sys driver in CA Host-Based Intrusion Prevention System (HIPS) r8, as u
CVE-2007-4967 MEDIUM 4.4 DOWNGRADE Online Armor Personal Firewall 2.0.1.215 does not properly validate certain parameters to System Service Descr
CVE-2006-6623 HIGH 7.2 DOWNGRADE DOWNGRADE Sygate Personal Firewall 5.6.2808 relies on the Process Environment Block (PEB) to identify a process, which a
CVE-2006-6622 HIGH 7.2 DOWNGRADE DOWNGRADE Soft4Ever Look 'n' Stop (LnS) 2.05p2 before 20061215 relies on the Process Environment Block (PEB) to identify

References

← Back to latest CVEs