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iOSOperating system · Cisco

CVE-2011-3274

MEDIUM · 6.1 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 →
66/100
Remediation priority · Elevated
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 Cisco IOS 12.2SRE before 12.2(33)SRE4, 15.0, and 15.1, and IOS XE 2.1.x through 3.3.x, when an MPLS domain is configured, allows remote attackers to cause a denial of service (device crash) via a crafted IPv6 packet, related to an expired MPLS TTL, aka Bug ID CSCto07919.

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 Cisco IOS and IOS XE allows remote attackers to crash devices via crafted IPv6 packets when an MPLS domain is configured. The issue occurs when an IPv6 packet with an expired MPLS TTL is processed, causing a denial of service. The vulnerability affects IOS 12.2SRE before 12.2(33)SRE4, IOS 15.0/15.1, and IOS XE 2.1.x through 3.3.x.

MitigationApply the vendor-supplied software update (IOS 12.2(33)SRE4 or later, or corresponding patched versions for IOS 15.x and IOS XE). Ensure MPLS configurations are backed up before upgrading and test IPv6/MPLS functionality after applying the patch.

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
Affected:= 12.2\(33\)sre= 12.2\(33\)sre0a= 12.2\(33\)sre1= 12.2\(33\)sre2= 12.2\(33\)sre3= 12.2sre= 15.0= 15.1
Ios XeOperating system
Affected:= 2.1.0= 2.1.1= 2.1.2= 2.2.1= 2.2.2= 2.2.3= 2.3.0= 2.3.1= 2.3.2= 2.4.0= 2.4.1= 2.4.2

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
Adjacent
Complexity
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete

AV:A/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. Determine the IOS or IOS XE version
    Run 'show version' or 'show version | include Version' to obtain the installed software version.
    Affected if The version is 12.2SRE before 12.2(33)SRE4, or is 15.0 or 15.1, or is any IOS XE 2.1.x through 3.3.x version.
  2. Verify IPv6 is enabled
    Run 'show ipv6 interface brief' to check if any interfaces have IPv6 configured.
    Affected if IPv6 is enabled on any interface.
  3. Confirm MPLS is configured
    Run 'show mpls interfaces' or 'show running-config | include mpls' to check for MPLS domain or label switch router configuration.
    Affected if An MPLS domain or MPLS label switching is configured on the device.
  4. Check for MPLS label distribution protocol
    Run 'show mpls ldp neighbor' or 'show mpls traffic-eng tunnel' to verify LDP or TE tunnels are active.
    Affected if MPLS LDP or TE is operational.

The device is affected if it runs a vulnerable IOS/IOS XE version AND has both IPv6 enabled AND an MPLS domain configured, allowing crafted IPv6 packets with expired MPLS TTL to crash the device.

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 the vendor-supplied software update (IOS 12.2(33)SRE4 or later, or corresponding patched versions for IOS 15.x and IOS XE). Ensure MPLS configurations are backed up before upgrading and test IPv6/MPLS functionality after applying the patch.

Fix this in iOS Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,750
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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-2011-3274 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data