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Ios XeOperating system · Cisco

CVE-2011-3278

HIGH · 7.8 CVSS v2.0 Published 2011-10-03
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
87/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
Unspecified vulnerability in the NAT implementation in Cisco IOS 12.1 through 12.4 and 15.0 through 15.1, and IOS XE 3.1.xSG, allows remote attackers to cause a denial of service (device reload) by sending crafted SIP packets to UDP port 5060, aka Bug ID CSCti48483.

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 confidence

A vulnerability in the NAT implementation of Cisco IOS 12.1-12.4, 15.0-15.1, and IOS XE 3.1.xSG allows remote attackers to cause device reload (denial of service) by sending specially crafted SIP (Session Initiation Protocol) packets to UDP port 5060. The vulnerability is triggered during NAT processing of the malicious SIP traffic.

MitigationApply Cisco IOS/IOS XE software updates that address CSCti48483. At network perimeter devices, filter or block untrusted SIP traffic (UDP 5060) and implement rate-limiting on SIP ports to reduce attack surface until patches can be applied.

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
Ios XeOperating system
Affected:= 3.1.0sg= 3.1.1sg
iOSOperating system
Affected:= 12.1= 12.1e= 12.2= 12.2b= 12.2bc= 12.2bx= 12.2cx= 12.2cz= 12.2ew= 12.2ewa= 12.2ex= 12.2ey

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Check the Cisco IOS or IOS XE version
    Run 'show version' or 'show version | include Version' to retrieve the installed software version
    Affected if The version falls within 12.1 through 12.4, 15.0 through 15.1, or equals 3.1.0SG/3.1.1SG for IOS XE
  2. Verify if NAT is enabled
    Run 'show ip nat statistics' or 'show ip nat translations' to check if Network Address Translation is configured and active on the device
    Affected if NAT is actively configured and processing traffic on the device
  3. Confirm SIP ALG or NAT helper for SIP is enabled
    Run 'show service internal' or check the NAT configuration for 'ip nat service sip' or similar SIP ALG settings. Also check 'show running-config | include sip' for SIP-related features
    Affected if SIP application layer gateway (ALG) or SIP NAT helper is enabled in the NAT configuration
  4. Determine if UDP port 5060 is accessible on the device
    Run 'show ip socket' or 'show udp' to check if the device is listening on UDP port 5060, or review access lists and interface configurations for SIP traffic on UDP 5060
    Affected if The device is processing SIP traffic on UDP port 5060 through NAT

A user is affected if their device runs a vulnerable IOS/IOS XE version, has NAT enabled with SIP ALG support, and is processing SIP traffic on UDP port 5060.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco IOS/IOS XE software updates that address CSCti48483. At network perimeter devices, filter or block untrusted SIP traffic (UDP 5060) and implement rate-limiting on SIP ports to reduce attack surface until patches can be applied.

Fix this in Ios Xe Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2011-3278 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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