CVE-2004-1799
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 · uneditedPF in certain OpenBSD versions, when stateful filtering is enabled, does not limit packets for a session to the original interface, which allows remote attackers to bypass intended packet filters via spoofed packets to other interfaces.
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 · moderate confidencePF (Packet Filter) in older OpenBSD versions with stateful filtering enabled fails to enforce that packets belonging to an established session must return through the same interface they originated from. This allows attackers to send spoofed packets through alternate interfaces to bypass the firewall's intended filtering rules.
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= 3.0= 3.1= 3.2= 3.3= 3.4CVSS 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
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/C:P/I:P/A:P
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 checksWork through these to decide whether this CVE applies to you.
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Check OpenBSD versionRun 'uname -r' or check /var/run/dmesg.boot for the OpenBSD release versionAffected if Version is 3.0, 3.1, 3.2, 3.3, or 3.4
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Verify PF is loadedRun 'pfctl -si' or check if /etc/pf.conf exists and pf is active via 'pfctl -s all'Affected if PF firewall is enabled and running
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Identify stateful filtering rulesReview pf.conf rules for 'keep state' or 'modulate state' directives that enable stateful packet inspectionAffected if PF rules contain stateful filtering configuration (keep state, modulate state, or synproxy state)
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Check for antispoof or bidirectional interface enforcementReview pf.conf for 'antispoof' rules or interface-specific 'in' and 'out' rules that enforce bidirectional validationAffected if No antispoof rules and no explicit interface-bound filtering for stateful connections
System is affected if running OpenBSD 3.0-3.4 with PF enabled and using stateful filtering without antispoof protection or interface-specific bidirectional flow enforcement.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade to a patched OpenBSD version, or implement additional interface-specific filtering rules to enforce bidirectional packet flow validation for stateful connections.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2004-1799 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2004-1799 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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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