iOSOperating system · Cisco
CVE-2011-2578
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 · uneditedMemory leak in Cisco IOS 15.1 and 15.2 allows remote attackers to cause a denial of service (memory consumption) via malformed SIP packets on a NAT interface, aka Bug ID CSCts12366.
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 memory leak vulnerability in Cisco IOS versions 15.1 and 15.2 allows remote attackers to cause denial of service by sending malformed SIP (Session Initiation Protocol) packets through a NAT interface. The attack consumes device memory, potentially exhausting resources and rendering the device unavailable.
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
= 15.1= 15.2CVSS 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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Check the exact Cisco IOS versionRun 'show version' and locate the 'IOS' line showing the version number (for example, 'Version 15.1' or 'Version 15.2')Affected if The version is exactly 15.1 or exactly 15.2 (note: this vulnerability affects only these specific point releases, not the entire 15.1 or 15.2 families)
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Verify SIP is enabled on the deviceRun 'show running-config | include sip' or look for SIP-related configuration in the running config. Also try 'show sip' if available on your platform.Affected if SIP protocol handling is configured or enabled on the device
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Confirm NAT is configuredRun 'show ip nat statistics' or 'show running-config | include ip nat' to verify Network Address Translation is active.Affected if NAT is configured on the device
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Check for SIP traffic through NATRun 'show ip nat translations' and look for entries involving SIP port 5060, or monitor traffic on interfaces handling SIP calls.Affected if SIP traffic is being processed through a NAT interface (the attack requires SIP packets to traverse NAT)
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Review memory usage on the deviceRun 'show memory summary' or 'show processes memory' to check current memory utilization levels.Affected if Memory usage is abnormally high or increasing over time without explanation (indicative of the memory leak)
You are affected only if you are running exactly IOS 15.1 or 15.2, have SIP enabled, have NAT configured, and are processing SIP traffic through a NAT interface.
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 Cisco IOS to a patched version that addresses this vulnerability. As an interim measure, consider filtering or rate-limiting SIP traffic on NAT interfaces until the upgrade can be performed.
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-2011-2578 — 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-2011-2578 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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