CVE-2006-0839: The frag3 preprocessor in Sourcefire Snort 2.4.3 does not properly reassemble certain fragmented packets with

Routine

MEDIUM 5.0DOWNGRADE

CVE-2006-0839 is a medium-severity flaw (CVSS 5.0) affecting snort. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The frag3 preprocessor in Sourcefire Snort 2.4.3 does not properly reassemble certain fragmented packets with IP options, which allows remote attackers to evade detection of certain attacks, possibly related to IP option lengths.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	1.4% (top 27%)
CISA exploited list	No
Published	2006-02-22
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: sourcefire

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

Am I affected?

Timeline

2006-02-22 02:02 UTCPublished CVE record published
2026-06-16 22:21 UTCUpdated Record last modified

sourcefire snort DOWNGRADE

Affected: 2.4.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.4.3

1. Check installed version

apt-cache policy snort || rpm -q snort || snort --version

2. No fixed release: DOWNGRADE to a release before 2.4.3 (Debian / Ubuntu)

apt-cache madison snort sudo apt install snort=<VERSION_BEFORE_2.4.3> sudo apt-mark hold snort

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

dnf --showduplicates list snort sudo dnf downgrade snort-<VERSION_BEFORE_2.4.3> sudo dnf versionlock add snort

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.

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-2006-0839?

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

Is CVE-2006-0839 being exploited?

CVE-2006-0839 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-2006-0839 affect?

CVE-2006-0839 affects snort. Severity is medium (CVSS 5.0). The frag3 preprocessor in Sourcefire Snort 2.4.3 does not properly reassemble certain fragmented packets with IP options, which allows remote attackers to evade detection of certain attacks, possibly related to IP option lengths.

How urgent is CVE-2006-0839?

Priority 36/100. No elevated risk signals yet.

Software pages

Suricata and Snort vulnerabilities

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References

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