CVE-2011-3326
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 · uneditedThe ospf_flood function in ospf_flood.c in ospfd in Quagga before 0.99.19 allows remote attackers to cause a denial of service (daemon crash) via an invalid Link State Advertisement (LSA) type in an IPv4 Link State Update message.
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 confidenceThe ospf_flood function in Quagga's ospfd daemon fails to properly validate the Link State Advertisement (LSA) type field in incoming IPv4 Link State Update messages. When a malformed LSA with an invalid type is processed, it triggers a NULL pointer dereference or similar memory corruption causing the daemon to crash, resulting in complete OSPF routing failure.
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<= 0.99.18= 0.95= 0.96= 0.96.1= 0.96.2= 0.96.3= 0.96.4= 0.96.5= 0.97.0= 0.97.1= 0.97.2= 0.97.3CVSS 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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Confirm ospfd daemon is runningRun 'ps aux | grep ospfd' or 'systemctl status ospfd' to check if the OSPF daemon is activeAffected if ospfd is running - the vulnerability only applies when the daemon is active and processing OSPF packets
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Identify installed Quagga versionRun 'quagga -v' or 'rpm -q quagga' / 'dpkg -l quagga' to find the exact version number installedAffected if version is 0.95, 0.96, 0.96.1, 0.96.2, 0.96.3, 0.96.4, 0.96.5, 0.97.0, 0.97.1, 0.97.2, 0.97.3, or any version <= 0.99.18
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Verify OSPF is configuredCheck ospfd configuration files in /etc/quagga/ospfd.conf or use 'vtysh -c "show ip ospf interface"' to list active OSPF interfacesAffected if OSPF interfaces are configured and actively participating - the daemon must be actively processing OSPF Link State Updates for exploitation
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Confirm ospf_flood function is reachableReview ospfd logs for recent LSA-related activity or examine if the daemon has been receiving OSPF packets on any interface using 'tcpdump -i <interface> ospf'Affected if OSPF neighbors are established and exchanging LSAs - the vulnerable code path is triggered when processing incoming Link State Update messages
If ospfd is running on Quagga version 0.95 through 0.99.18 and OSPF is actively processing neighbors, the environment is vulnerable to crash via malformed LSA packets.
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 Quagga to version 0.99.19 or later which includes proper LSA type validation in the ospf_flood function. If immediate upgrade is not feasible, implement strict OSPF neighbor authentication and filter untrusted interface peers to reduce attack surface.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2011-3326 — 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-2011-3326 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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