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SnortApplication · Sourcefire

CVE-2006-0839

MEDIUM · 5.0 CVSS v2.0 Published 2006-02-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The frag3 preprocessor in Sourcefire Snort 2.4.3 fails to properly reassemble fragmented packets that contain IP options. This flaw allows remote attackers to craft malicious packets with specific IP option configurations that bypass Snort's intrusion detection, evading detection of attacks that would normally be flagged.

MitigationUpgrade Snort to a version that addresses the frag3 IP option reassembly vulnerability, or apply any available vendor patches for this issue.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SnortApplication
Affected:= 2.4.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
None

AV:N/AC:L/Au:N/C:N/I:P/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify Snort is installed
    Run `snort -V` or `snort --version` to confirm Snort is present and retrieve its version number
    Affected if Snort is not installed or the command fails
  2. Confirm Snort version is 2.4.3
    Compare the installed version output from the previous step to the affected version 2.4.3
    Affected if The version shown is exactly 2.4.3
  3. Locate Snort configuration file
    Find the snort.conf file (commonly in /etc/snort/ or the Snort installation directory)
    Affected if No configuration file exists or can be found
  4. Verify frag3 preprocessor is enabled
    Inspect the snort.conf file for lines containing 'preprocessor frag3' or 'frag3' directives
    Affected if The frag3 preprocessor is enabled in the configuration
  5. Check IP options handling configuration
    Look in snort.conf for any frag3-related parameters, particularly any governing IP options or defragmentation settings
    Affected if Frag3 is configured with IP options reassembly enabled or not explicitly disabled

A user is affected if Snort version 2.4.3 is installed with the frag3 preprocessor enabled and IP options fragment handling is active in the configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Snort to a version that addresses the frag3 IP option reassembly vulnerability, or apply any available vendor patches for this issue.

Fix this in Snort Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,570
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2006-0839 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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