Linux KernelOperating system · Linux
CVE-2003-0467
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 · uneditedUnknown vulnerability in ip_nat_sack_adjust of Netfilter in Linux kernels 2.4.20, and some 2.5.x, when CONFIG_IP_NF_NAT_FTP or CONFIG_IP_NF_NAT_IRC is enabled, or the ip_nat_ftp or ip_nat_irc modules are loaded, allows remote attackers to cause a denial of service (crash) in systems using NAT, possibly due to an integer signedness error.
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 confidenceInteger signedness error in the ip_nat_sack_adjust function of Netfilter in Linux kernels 2.4.20 and some 2.5.x versions. Triggered when FTP or IRC NAT modules (CONFIG_IP_NF_NAT_FTP/CONFIG_IP_NF_NAT_IRC or their loadable equivalents) are enabled, allowing remote attackers to cause a denial of service (crash) on systems using NAT.
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
Linux KernelOperating system
= 2.4.20= 2.4.21CVSS 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
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/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 the running kernel versionRun 'uname -r' or 'cat /proc/version' to determine the kernel versionAffected if The kernel version is 2.4.20 or 2.4.21 exactly, as these are the specifically affected versions listed in the CVE
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Identify if the FTP NAT module is loaded or built-inRun 'lsmod | grep ip_nat_ftp' to check if the module is loaded, or examine the kernel config file (typically /boot/config-$(uname -r) or /proc/config.gz) for CONFIG_IP_NF_NAT_FTP settingsAffected if The module ip_nat_ftp is loaded (lsmod shows it) OR the kernel config shows CONFIG_IP_NF_NAT_FTP=y (built-in) or CONFIG_IP_NF_NAT_FTP=m (loadable module)
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Identify if the IRC NAT module is loaded or built-inRun 'lsmod | grep ip_nat_irc' to check if the module is loaded, or examine the kernel config file for CONFIG_IP_NF_NAT_IRC settingsAffected if The module ip_nat_irc is loaded (lsmod shows it) OR the kernel config shows CONFIG_IP_NF_NAT_IRC=y (built-in) or CONFIG_IP_NF_NAT_IRC=m (loadable module)
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Confirm Netfilter NAT is in useCheck if iptables NAT rules are active by running 'iptables -t nat -L -n' or checking for any NAT-related iptables rulesAffected if There are active NAT rules in iptables, particularly those using the nat table, which would invoke the vulnerable code path when the affected modules are loaded
A system is affected if it runs kernel 2.4.20 or 2.4.21 AND has either the ip_nat_ftp or ip_nat_irc module loaded (or built-in), regardless of whether active NAT rules exist, because the mere presence of these modules enables the vulnerable ip_nat_sack_adjust function code.
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 Linux kernel version that includes the fix for this vulnerability, or disable the affected NAT modules (ip_nat_ftp, ip_nat_irc) if not required. For legacy systems, apply the upstream kernel patch addressing the signedness issue in ip_nat_sack_adjust.
Fix this in Linux Kernel
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 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 $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2003-0467 — 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-2003-0467 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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- Version or environment caveats, and links to real fixes
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