iOSOperating system · Cisco
CVE-2001-1097
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 routers and switches running IOS 12.0 through 12.2.1 allows a remote attacker to cause a denial of service via a flood of UDP packets.
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 confidenceThis CVE describes a denial-of-service vulnerability in Cisco routers and switches running IOS versions 12.0 through 12.2.1. A remote attacker can cause a DoS condition by flooding the affected device with a large volume of UDP packets, potentially causing the device to become unresponsive or crash.
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
= 12.0= 12.0\(1\)= 12.0\(2\)= 12.0\(3\)= 12.0\(4\)= 12.0\(5\)= 12.0\(6\)= 12.0\(7\)t= 12.1= 12.2CVSS 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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Check the IOS version running on the deviceRun 'show version' command from the device console or via SNMP/remote access. Look for the version number in the output (e.g., 'Cisco IOS Software, Version 12.1' or 'Version 12.2(1)')Affected if The displayed version falls within 12.0 through 12.2.1, inclusive (versions 12.0, 12.0(1) through 12.0(7)t, 12.1, 12.2, 12.2(1), and any 12.2.1x release)
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Confirm the device is a Cisco router or switchVerify the device model from 'show version' output or physical labeling. This vulnerability affects Cisco routers and switches specifically.Affected if The device is a Cisco router or switch running the vulnerable IOS version range
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Verify UDP traffic can reach the deviceCheck for active interfaces with 'show ip interface brief' and confirm UDP-based services (like SNMP, DNS, or other UDP listeners) may be accessible from untrusted networks.Affected if The device has any active layer 3 interfaces with UDP services exposed to network segments where an attacker could flood UDP packets
A device is affected if it is a Cisco router or switch running IOS versions 12.0 through 12.2.1 with accessible network interfaces, as the vulnerability triggers when the device processes a flood of UDP packets.
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 dataUpgrade IOS to a version beyond 12.2.1 that includes the fix, or implement ACLs and rate-limiting on perimeter devices to filter or throttle suspicious UDP traffic.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2001-1097 — 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-2001-1097 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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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.
- 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
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