iOSOperating system · Cisco
CVE-2013-5469
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 TCP implementation in Cisco IOS does not properly implement the transitions from the ESTABLISHED state to the CLOSED state, which allows remote attackers to cause a denial of service (flood of ACK packets) via a crafted series of ACK and FIN packets, aka Bug ID CSCtz14399.
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 TCP implementation in Cisco IOS contains a state machine flaw where transitions from ESTABLISHED to CLOSED state are not properly handled. Attackers can send a crafted series of ACK and FIN packets to trigger this condition, causing the affected device to generate an ACK flood (denial of service).
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
all versionsCVSS 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
- M
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:N/AC:M/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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Confirm device runs Cisco IOSExecute 'show version' and examine the output. Look for 'Cisco IOS Software' in the software description. IOS will show 'IOS' in the image name; IOS-XE will show 'XE'.Affected if The device is confirmed to be running Cisco IOS (not IOS-XE, NX-OS, or other platforms)
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Identify TCP-related process consumptionExecute 'show processes cpu history' and 'show ip traffic' to observe abnormal TCP-related CPU usage or packet statistics. Also use 'show tcp statistics' to examine ACK and FIN packet counts.Affected if CPU usage is abnormally high from TCP processes or ACK packet counts are excessively elevated
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Check for TCP state anomaliesExecute 'show tcp brief all' to view active TCP connections. Look for connections in unusual states or rapid state transitions between ESTABLISHED and CLOSED.Affected if Connections show rapid cycling between ESTABLISHED and CLOSED states without normal FIN handshake completion
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Monitor for ACK flood conditionUse 'show interface' and 'show ip traffic' repeatedly to observe inbound ACK packet rates. Compare against baseline normal traffic patterns.Affected if Inbound ACK packet volume is dramatically elevated beyond normal baseline without corresponding legitimate traffic increase
The environment is affected if the device runs Cisco IOS and exhibits symptoms of ACK flooding or abnormal TCP state transitions under normal network conditions.
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 patch for Bug ID CSCtz14399. Until patched, consider implementing traffic filtering or ACLs to limit suspicious ACK/FIN packet patterns at network boundaries.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-5469 — 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-2013-5469 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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