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iOSOperating system · Cisco

CVE-2008-3805

HIGH · 8.5 CVSS v2.0 Published 2008-09-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
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 12.0 through 12.4 on Cisco 10000, uBR10012 and uBR7200 series devices handles external UDP packets that are sent to 127.0.0.0/8 addresses intended for IPC communication within the device, which allows remote attackers to cause a denial of service (device or linecard reload) via crafted UDP packets, a different vulnerability than CVE-2008-3806.

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

Cisco IOS 12.0-12.4 on 10000, uBR10012 and uBR7200 series devices incorrectly processes external UDP packets destined for 127.0.0.0/8 loopback addresses. These packets, which should never originate externally, are mishandled as internal IPC communication, causing the device or linecard to reload, resulting in denial of service.

MitigationFilter external UDP traffic destined to 127.0.0.0/8 at the network perimeter using ACLs, and upgrade to a patched Cisco IOS version beyond 12.4.

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:= 12.2b= 12.2ca= 12.2l= 12.2rc= 12.2s= 12.2t= 12.2zx= 12.3bc= 12.3t= 12.3xi= 12.4

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
Partial
Availability
Complete

AV:N/AC:L/Au:N/C:N/I:P/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. Identify the device hardware model
    Run 'show version' or 'show inventory' and look for the platform name
    Affected if The device is NOT a Cisco 10000, uBR10012, or uBR7200 series router - these are the only affected platforms
  2. Determine the Cisco IOS version
    Run 'show version' and note the IOS version string (for example: '12.4(15)T1')
    Affected if The IOS version falls within 12.0 through 12.4 inclusive, specifically versions 12.2b, 12.2ca, 12.2l, 12.2rc, 12.2s, 12.2t, 12.2zx, 12.3bc, 12.3t, 12.3xi, or 12.4; compare your exact version against these affected trains
  3. Verify external network exposure
    Review interface configurations with 'show running-config' or 'show ip interface brief' and identify which interfaces face external/untrusted networks
    Affected if The device has interfaces configured on external/Internet-facing networks (such as WAN interfaces, cable interfaces on uBR devices, or any interface connected to untrusted networks) that can receive UDP traffic from untrusted sources
  4. Check if UDP traffic from external sources is permitted
    Review applied access-lists with 'show access-lists' on external-facing interfaces; verify whether ACLs explicitly block or permit UDP packets
    Affected if There are NO ACLs filtering incoming UDP packets on external-facing interfaces, or ACLs permit UDP traffic destined to any IP range including 127.0.0.0/8

A user is affected if they run Cisco IOS 12.0-12.4 on a 10000, uBR10012, or uBR7200 series device with externally accessible interfaces that can receive UDP packets without proper filtering for destination 127.0.0.0/8.

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 external UDP traffic destined to 127.0.0.0/8 at the network perimeter using ACLs, and upgrade to a patched Cisco IOS version beyond 12.4.

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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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-2008-3805 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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