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iOSOperating system · Cisco

CVE-2011-2057

HIGH · 7.5 CVSS v3.1 Published 2011-10-22
Fix available
A fix is available. Upgrade to 12.2 or later.
See remediation →
84/100
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
The cat6000-dot1x component in Cisco IOS 12.2 before 12.2(33)SXI7 does not properly handle (1) a loop between a dot1x enabled port and an open-authentication dot1x enabled port and (2) a loop between a dot1x enabled port and a non-dot1x port, which allows remote attackers to cause a denial of service (traffic storm) via unspecified vectors that trigger many Spanning Tree Protocol (STP) Bridge Protocol Data Unit (BPDU) frames, aka Bug ID CSCtq36327.

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

The cat6000-dot1x component in Cisco IOS 12.2 before 12.2(33)SXI7 fails to properly handle loop conditions when either a dot1x-enabled port connects to an open-authentication dot1x-enabled port, or a dot1x-enabled port connects to a non-dot1x port. This allows remote attackers to trigger a traffic storm via excessive Spanning Tree Protocol BPDU frames, causing denial of service.

MitigationUpgrade Cisco IOS to version 12.2(33)SXI7 or later. Consider enabling Loop Guard or BPDU Guard on dot1x-enabled ports as a defensive measure while planning the upgrade.

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, < 12.2\(33\)sxi7

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
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 version
    Run 'show version' on the device and locate the IOS version string (e.g., 12.2(33)SXI5)
    Affected if The installed version is 12.2 or higher but lower than 12.2(33)SXI7 (for example, 12.2(33)SXI5 is affected)
  2. Verify if 802.1X (dot1x) is enabled
    Run 'show dot1x all' or 'show dot1x summary' to see if dot1x is active on any interfaces
    Affected if Any interface shows dot1x in an enabled or active state
  3. Identify dot1x port configurations
    Run 'show running-config | include dot1x' or 'show interface switchport | include dot1x' to list ports with dot1x authentication configured
    Affected if Any ports are configured with dot1x authentication (port-control set to auto or force-authorized)
  4. Check for open-authentication dot1x ports
    Run 'show dot1x all' and look for interfaces with 'PortControl' set to 'auto' and any open-authentication settings; also check 'show running-config interface' for dot1x port-control commands
    Affected if Any dot1x-enabled port is set to open-authentication mode or connects to a non-dot1x port
  5. Check spanning tree and loop protection status
    Run 'show spanning-tree summary' and 'show spanning-tree interface' to examine STP BPDU handling and loop guard or BPDU guard configuration
    Affected if Loop Guard or BPDU Guard is NOT enabled on dot1x-enabled ports, indicating the protective measure is missing

You are affected if the device runs Cisco IOS version 12.2 or higher but lower than 12.2(33)SXI7 AND has dot1x-enabled ports without adequate loop protection.

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
Upgrade available Upgrade to 12.2 or later
Fixed in 12.2
Interim mitigation

Upgrade Cisco IOS to version 12.2(33)SXI7 or later. Consider enabling Loop Guard or BPDU Guard on dot1x-enabled ports as a defensive measure while planning the upgrade.

Fix this in iOS Scoped from the published advisory
  • Consultation8.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,240
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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-2011-2057 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