iOSOperating system · Cisco
CVE-2008-3806
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 · uneditedCisco IOS 12.0 through 12.4 on Cisco 10000, uBR10012 and uBR7200 series devices handles external UDP packets that are sent to 127.0.0.0/8 addresses intended for IPC communication within the device, which allows remote attackers to cause a denial of service (device or linecard reload) via crafted UDP packets, a different vulnerability than CVE-2008-3805.
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 confidenceCisco IOS 12.0-12.4 on 10000, uBR10012, and uBR7200 series devices improperly processes external UDP packets sent to 127.0.0.0/8 loopback addresses. These addresses are intended for internal IPC communication within the device, but the device accepts and processes externally-received UDP packets destined for these addresses, causing the device or linecard to reload.
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
iOSOperating system
= 12.0s= 12.0sl= 12.0st= 12.2sb= 12.2sca= 12.2src= 12.2zx= 12.3bc= 12.3t= 12.3xi= 12.4CVSS 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
- None
- Integrity
- Partial
- Availability
- Complete
AV:N/AC:L/Au:N/C:N/I:P/A:C
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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Identify the device modelRun 'show version' or check the hardware inventory to confirm the device is a Cisco 10000, uBR10012, or uBR7200 series routerAffected if The device model is one of the 10000, uBR10012, or uBR7200 series
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Identify the Cisco IOS versionRun 'show version' and note the IOS release number (e.g., 12.4, 12.3xi, 12.2sca)Affected if The IOS version matches one of: 12.0s, 12.0sl, 12.0st, 12.2sb, 12.2sca, 12.2src, 12.2zx, 12.3bc, 12.3t, 12.3xi, or 12.4
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Determine if the device is exposed to external UDP trafficReview the network topology and access control lists to determine whether the device's external interfaces can receive UDP packets from untrusted sourcesAffected if The device has externally-facing interfaces that can receive UDP traffic from untrusted networks
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Check if UDP traffic to 127.0.0.0/8 can reach the deviceInspect inbound ACLs or firewall filters on the device's external interfaces to see if UDP packets destined to any 127.0.0.0/8 address are permitted or blockedAffected if There are no filters blocking inbound UDP packets destined to 127.0.0.0/8 addresses on external interfaces
The device is affected if it is a Cisco 10000, uBR10012, or uBR7200 series router running a vulnerable IOS version (12.0s through 12.4) AND the device can receive external UDP traffic destined to 127.0.0.0/8 addresses.
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 Cisco IOS version; as interim mitigation, filter UDP traffic destined to 127.0.0.0/8 at network edges to prevent external packets from reaching the device loopback interface.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2008-3806 — 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-2008-3806 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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