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iOSOperating system · Cisco

CVE-2016-6473

MEDIUM · 6.5 CVSS v3.0 Published 2016-12-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
70/100
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
A vulnerability in Cisco IOS on Catalyst Switches and Nexus 9300 Series Switches could allow an unauthenticated, adjacent attacker to cause a Layer 2 network storm. More Information: CSCuu69332, CSCux07028. Known Affected Releases: 15.2(3)E. Known Fixed Releases: 12.2(50)SE4 12.2(50)SE5 12.2(50)SQ5 12.2(50)SQ6 12.2(50)SQ7 12.2(52)EY4 12.2(52)SE1 12.2(53)EX 12.2(53)SE 12.2(53)SE1 12.2(53)SE2 12.2(53)SG10 12.2(53)SG11 12.2(53)SG2 12.2(53)SG9 12.2(54)SG1 12.2(55)EX3 12.2(55)SE 12.2(55)SE1 12.2(55)SE10 12.2(55)SE2 12.2(55)SE3 12.2(55)SE4 12.2(55)SE5 12.2(55)SE6 12.2(55)SE7 12.2(55)SE8 12.2(55)SE9 12.2(58)EZ 12.2(58)SE1 12.2(58)SE2 12.2(60)EZ 12.2(60)EZ1 12.2(60)EZ2 12.2(60)EZ3 12.2(60)EZ4 12.2(60)EZ5 12.2(60)EZ6 12.2(60)EZ7 12.2(60)EZ8 15.0(1)EY2 15.0(1)SE 15.0(1)SE2 15.0(1)SE3 15.0(2)EA 15.0(2)EB 15.0(2)EC 15.0(2)ED 15.0(2)EH 15.0(2)EJ 15.0(2)EJ1 15.0(2)EK1 15.0(2)EX 15.0(2)EX1 15.0(2)EX3 15.0(2)EX4 15.0(2)EX5 15.0(2)EY 15.0(2)EY1 15.0(2)EY2 15.0(2)EZ 15.0(2)SE 15.0(2)SE1 15.0(2)SE2 15.0(2)SE3 15.0(2)SE4 15.0(2)SE5 15.0(2)SE6 15.0(2)SE7 15.0(2)SE9 15.0(2)SG10 15.0(2)SG3 15.0(2)SG6 15.0(2)SG7 15.0(2)SG8 15.0(2)SG9 15.0(2a)EX5 15.1(2)SG 15.1(2)SG1 15.1(2)SG2 15.1(2)SG3 15.1(2)SG4 15.1(2)SG5 15.1(2)SG6 15.2(1)E 15.2(1)E1 15.2(1)E2 15.2(1)E3 15.2(1)EY 15.2(2)E 15.2(2)E3 15.2(2b)E.

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

This vulnerability in Cisco IOS on Catalyst Switches and Nexus 9300 Series Switches allows an unauthenticated, adjacent attacker (on the same Layer 2 network segment) to cause a Layer 2 network storm by triggering excessive broadcast or multicast traffic, resulting in denial of service.

MitigationUpgrade Cisco IOS to one of the fixed releases listed in the Cisco advisory. For immediate workarounds, consider network segmentation or VLAN isolation to limit the attack surface to trusted adjacent segments.

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:= 15.0\(2\)se8= 15.2\(2\)e1= 15.2\(2\)e2= 15.2\(2a\)e1= 15.2\(3\)e= 15.2\(3\)e1= 15.2\(3a\)e

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

CVSS:3.0/AV:A/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. Identify the switch model
    Run 'show version' or 'show inventory' to confirm the device is a Cisco Catalyst Switch or Nexus 9300 Series Switch
    Affected if The device is a Cisco Catalyst Switch or Nexus 9300 Series Switch
  2. Check the Cisco IOS version
    Run 'show version' and locate the IOS version string (typically displayed as something like 15.0(2)se8 or 15.2(2)e1)
    Affected if The installed IOS version exactly matches one of these: 15.0(2)se8, 15.2(2)e1, 15.2(2)e2, 15.2(2a)e1, 15.2(3)e, 15.2(3)e1, or 15.2(3a)e
  3. Verify Layer 2 network exposure
    Review the network topology and port configurations to determine if untrusted adjacent devices can connect to the same Layer 2 segment (VLAN) as the switch
    Affected if Untrusted or unfiltered devices can gain physical or logical access to the same Layer 2 broadcast domain as the switch
  4. Check for broadcast/multicast storm indicators
    Run 'show interface | include babble' or monitor CPU and bandwidth utilization during periods of high traffic. Use 'show spanning-tree detail' to check for topology instability
    Affected if Unexplained high broadcast/multicast traffic volumes or CPU spikes are observed, particularly from edge ports

You are affected if you run Cisco IOS version 15.0(2)se8, 15.2(2)e1, 15.2(2)e2, 15.2(2a)e1, 15.2(3)e, 15.2(3)e1, or 15.2(3a)e on a Catalyst Switch or Nexus 9300 Series Switch, and untrusted adjacent attackers can access the same Layer 2 segment.

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

Upgrade Cisco IOS to one of the fixed releases listed in the Cisco advisory. For immediate workarounds, consider network segmentation or VLAN isolation to limit the attack surface to trusted adjacent segments.

Fix this in iOS 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-2016-6473 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
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  • 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