iOSOperating system · Cisco
CVE-2013-5477
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 T1/E1 driver-queue functionality in Cisco IOS 12.2 and 15.0 through 15.3, when an HDLC32 driver is used, allows remote attackers to cause a denial of service (interface queue wedge) via bursty network traffic, aka Bug ID CSCub67465.
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 confidenceThis is a denial-of-service vulnerability in Cisco IOS affecting the T1/E1 driver-queue functionality when the HDLC32 driver is used. Remote attackers can send bursty network traffic to cause an interface queue wedge, effectively locking up the affected interface and preventing legitimate traffic from being processed.
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
= 12.2= 15.0= 15.1= 15.2= 15.3CVSS 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
- Complete
AV:N/AC:L/Au:N/C:N/I:N/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 OS platformRun 'show version' and confirm the device is running Cisco IOS (not IOS-XE, NX-OS, or ASA)Affected if The device does not run Cisco IOS - this CVE only affects Cisco IOS
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Check the IOS versionRun 'show version' and note the software version (for example, 15.1(4)M2)Affected if The version falls outside the 12.2, 15.0, 15.1, 15.2, or 15.3 trains - only these specific version ranges are affected
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Determine if T1/E1 interfaces existRun 'show ip interface brief' or 'show controllers t1' to list T1/E1 interface namesAffected if No T1/E1 interfaces are present - the vulnerability requires T1/E1 interfaces to be exploitable
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Verify HDLC32 driver usage on T1/E1 interfacesRun 'show controllers t1 [interface]' and look for HDLC32 in the driver information or check the encapsulation type with 'show interface [interface]'Affected if HDLC32 driver is not in use on the T1/E1 interface - the vulnerability only triggers when HDLC32 is the active driver
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Check interface queue statusRun 'show interface [t1/e1-interface]' and examine the input queue (hold queue) for signs of wedging or excessive dropsAffected if The interface input queue shows signs of being wedged or has high drop counts, which may indicate exploitation
A device is affected if it runs Cisco IOS versions 12.2, 15.0, 15.1, 15.2, or 15.3 and has T1/E1 interfaces utilizing the HDLC32 driver, making those specific interfaces vulnerable to queue wedge and denial of service.
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 relevant Cisco IOS security update for Bug ID CSCub67465 to all affected devices. As a workaround, consider implementing traffic rate limiting or access controls on affected interfaces until the patch can be deployed.
Fix this in iOS
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 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 $2,880.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-5477 — 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-2013-5477 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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