iOSOperating system · Cisco
CVE-2011-4015
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 15.2S allows remote attackers to cause a denial of service (interface queue wedge) via malformed UDP traffic on port 465, aka Bug ID CSCts48300.
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 confidenceA remote attacker can send malformed UDP packets to port 465 on Cisco IOS 15.2S devices, causing the interface queue to become wedged (stuck in a deadlock state). This results in denial of service as the affected interface can no longer process traffic normally.
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
= 15.2sCVSS 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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Verify Cisco IOS version is 15.2SExecute 'show version' on the device and locate the IOS version string in the output. Look for a version number matching '15.2S' exactly.Affected if The IOS version string shows 15.2S (e.g., 15.2(1)S, 15.2(2)S, etc.)
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Confirm port 465 is accessible or configuredReview the device configuration with 'show running-config' and search for any references to port 465, or use 'show ip sockets' or 'show udp' if available to see if port 465 is bound to a service.Affected if Port 465 is actively listening, configured as a service, or exposed on an accessible interface
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Check interface queue status for wedged stateExecute 'show interfaces' for each active interface and examine the output for signs of queue wedging. Look for indicators such as the interface showing 'Input queue' with high drops or stuck packets, or the interface appearing up but not forwarding traffic.Affected if An interface shows as up/up but has an input queue that appears frozen or stuck, with traffic not being processed despite the interface status indicating it is operational
The device is affected if it runs exactly Cisco IOS 15.2S, has port 465 exposed or configured, and shows an interface in a wedged/stuck state with traffic not being processed.
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 dataApply the Cisco IOS update that addresses Bug ID CSCts48300, or implement ACL rules on ingress interfaces to filter or drop malformed UDP traffic destined for port 465.
Fix this in iOS
Scoped from the published advisory
- Consultation3.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,592.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-4015 — 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-2011-4015 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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