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CatosOperating system · Cisco

CVE-2008-4963

HIGH · 7.1 CVSS v2.0 Published 2008-11-06
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
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 VLAN Trunking Protocol (VTP) implementation on Cisco IOS and CatOS, when the VTP operating mode is not transparent, allows remote attackers to cause a denial of service (device reload or hang) via a crafted VTP packet sent to a switch interface configured as a trunk port.

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 confidence

This CVE targets Cisco IOS and CatOS switches running VTP (VLAN Trunking Protocol). When VTP is configured in server or client mode (not transparent), a remote attacker can send a maliciously crafted VTP packet to a trunk port, triggering a denial of service that causes the affected switch to reload or hang.

MitigationSet VTP mode to transparent on affected switches to prevent processing of external VTP updates, or apply Cisco's available patches/workarounds for this vulnerability.

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
CatosOperating system
Affected:all versions
iOSOperating system
Affected:all versions

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
M
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete

AV:N/AC:M/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. Confirm device is a Cisco IOS or CatOS switch
    Run 'show version' and look for Cisco IOS or Catalyst OS in the output, or check the device model (e.g., Catalyst 2950, 3560, 4500, 6500 series)
    Affected if Device is a Cisco switch running IOS or CatOS
  2. Check if VTP is configured
    Run 'show vtp status' (for IOS) or 'show vtpd status' (for CatOS) and examine the output
    Affected if VTP is enabled and a domain name is configured
  3. Determine the VTP mode
    From the 'show vtp status' output, locate the 'Mode' field or 'VTP Operating Mode' line
    Affected if Mode is set to 'Server' or 'Client' (not 'Transparent' or 'Off')
  4. Verify trunk ports exist
    Run 'show interface trunk' (for IOS) or 'show trunk' (for CatOS) to list active trunk ports
    Affected if One or more trunk ports are configured and operational

The switch is affected if it is a Cisco IOS or CatOS switch with VTP configured in server or client mode (not transparent) and has at least one trunk port, as the attack vector requires receiving VTP packets on a trunk link.

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

Set VTP mode to transparent on affected switches to prevent processing of external VTP updates, or apply Cisco's available patches/workarounds for this vulnerability.

Fix this in Catos Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2008-4963 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