CVE-2004-0626: The tcp_find_option function of the netfilter subsystem in Linux kernel 2.6, when using iptables and TCP optio

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MEDIUM 5.0WATCHLISTMITIGATEMITIGATEMITIGATE

CVE-2004-0626 is a medium-severity flaw (CVSS 5.0) affecting linux, linux, linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The tcp_find_option function of the netfilter subsystem in Linux kernel 2.6, when using iptables and TCP options rules, allows remote attackers to cause a denial of service (CPU consumption by infinite loop) via a large option length that produces a negative integer after a casting operation to the char type.

Why this priority

On your watchlist

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	2.8% (top 14%)
CISA exploited list	No
Published	2004-12-06
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: conectiva · gentoo · linux · suse

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

Am I affected?

Timeline

2004-12-06 05:00 UTCPublished CVE record published
2026-06-16 22:06 UTCUpdated Record last modified

conectiva linux MITIGATE

Affected: 10

Fixed in: no fixed release known

Safe to downgrade to: a release before 10

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

gentoo linux MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

linux linux kernel MITIGATE

Affected: 2.6.0

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Downgrade not recommended

This is a core system component: downgrading can break the OS. Apply the distro update or the vendor mitigation.

suse suse linux MITIGATE

Affected: 8.0 · 8.1 · 8.2 · 9.0 · 9.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2004-0626?

linux: mitigate or apply the listed mitigation; linux: mitigate or apply the listed mitigation; linux kernel: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2004-0626 being exploited?

CVE-2004-0626 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-2004-0626 affect?

CVE-2004-0626 affects linux, linux, linux kernel. Severity is medium (CVSS 5.0). The tcp_find_option function of the netfilter subsystem in Linux kernel 2.6, when using iptables and TCP options rules, allows remote attackers to cause a denial of service (CPU consumption by infinite loop) via a large option length that p

How urgent is CVE-2004-0626?

Priority 44/100. On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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