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iOSOperating system · Cisco

CVE-2002-1768

MEDIUM · 5.0 CVSS v2.0 Published 2002-12-31
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
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
Cisco IOS 11.1 through 12.2, when HSRP support is not enabled, allows remote attackers to cause a denial of service (CPU consumption) via randomly sized UDP packets to the Hot Standby Routing Protocol (HSRP) port 1985.

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

When Cisco IOS 11.1 through 12.2 has HSRP disabled, the device still processes UDP packets sent to port 1985 (the HSRP multicast address), causing excessive CPU consumption and resulting in denial of service.

MitigationFilter/block UDP port 1985 at network boundaries using ACLs, or upgrade to a patched Cisco IOS version beyond 12.2.

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:= 11.1= 11.2= 12.0= 12.1= 12.2

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
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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Cisco IOS version
    Execute 'show version' on the device and locate the IOS release line (e.g., 'Cisco IOS Software, Version 12.2(15)T1')
    Affected if The version number starts with 11.1, 11.2, 12.0, 12.1, or 12.2
  2. Verify HSRP is disabled
    Execute 'show standby brief' or 'show ip interface [interface]' to check if HSRP is configured on any interface
    Affected if No HSRP standby groups are active (HSRP shows as disabled or not configured on all interfaces)
  3. Check for UDP port 1985 traffic
    Execute 'show ip traffic' or check interface packet counters for inbound UDP traffic on port 1985; alternatively, use 'show access-lists' if ACLs exist
    Affected if UDP packets destined to port 1985 are being received by the device
  4. Confirm CPU impact
    Monitor 'show processes cpu history' or 'show platform cpu packet' during periods of UDP 1985 traffic
    Affected if CPU utilization spikes correlate with incoming UDP port 1985 traffic despite HSRP being disabled

The device is affected if it runs Cisco IOS 11.1, 11.2, 12.0, 12.1, or 12.2, HSRP is not enabled, and the device is receiving UDP traffic on port 1985 which causes elevated CPU usage.

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

Filter/block UDP port 1985 at network boundaries using ACLs, or upgrade to a patched Cisco IOS version beyond 12.2.

Fix this in iOS 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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Scan for this in your stack

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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-2002-1768 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
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