Catalyst 2900Hardware / appliance · Cisco
CVE-2001-0566
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 · uneditedCisco Catalyst 2900XL switch allows a remote attacker to create a denial of service via an empty UDP packet sent to port 161 (SNMP) when SNMP is disabled.
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 confidenceThe Cisco Catalyst 2900XL switch contains a vulnerability where sending an empty UDP packet to port 161 (SNMP) causes a denial of service even when SNMP is disabled. This indicates improper packet handling in the SNMP subsystem that triggers a crash or hang condition regardless of the SNMP service state.
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
Catalyst 2900Hardware / appliance
= xlCVSS 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
- Partial
AV:N/AC:L/Au:N/C:N/I:N/A:P
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 checksWork through these to decide whether this CVE applies to you.
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Identify the device modelCheck the switch model via console, telnet, or SNMP sysDescr. Look for 'Catalyst 2900XL' or '2900' with XL variant in the hardware/firmware identification.Affected if The device is a Cisco Catalyst 2900XL switch (XL variant).
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Determine the firmware versionAccess the switch CLI and run 'show version' or check via SNMP sysDescr/sysVersion. Compare the IOS version against the affected release trains for the 2900XL.Affected if The firmware version is within any affected release train for the Catalyst 2900XL (no specific versions provided; compare to Cisco advisories).
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Verify SNMP service configurationCheck SNMP status via 'show snmp' or 'show running-config | include snmp' in the CLI. Confirm whether SNMP is enabled or disabled.Affected if SNMP may be enabled or disabled - the vulnerability triggers even when SNMP is disabled, so configuration alone does not prevent exposure.
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Test UDP port 161 accessibilityFrom an authorized management host, attempt a UDP probe to port 161 using 'nc -uvz <device_ip> 161' or nmap 'nmap -sU -p 161 <device_ip>'.Affected if UDP port 161 is reachable from an untrusted network segment.
You are affected if you operate a Cisco Catalyst 2900XL switch and UDP port 161 is accessible from your network, regardless of SNMP configuration status.
Generated from the published advisory. Verify against your own configuration.
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 dataSince the vulnerability persists despite SNMP being disabled, network segmentation and access control lists (ACLs) should be applied to restrict management access to trusted IPs. If available from Cisco, apply the appropriate firmware update for the Catalyst 2900XL.
Fix this in Catalyst 2900
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,880.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2001-0566 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2001-0566 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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