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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 9 Jun 2023.
iOSOperating system · Cisco

CVE-2004-1464

MEDIUM · 5.9 CVSS v3.1 Published 2004-12-31
Fix available
A fix is available. Upgrade to after 12.2 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Remotely reachable No privileges Zero-click Patch available

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 12.2(15) and earlier allows remote attackers to cause a denial of service (refused VTY (virtual terminal) connections), via a crafted TCP connection to the Telnet or reverse Telnet 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 · high confidence

CVE-2004-1464 affects Cisco IOS 12.2(15) and earlier, allowing remote attackers to cause a denial of service by sending a crafted TCP connection to the Telnet or reverse Telnet port, which results in refused VTY connections.

MitigationTo remediate this vulnerability, it is recommended to upgrade to a later version of Cisco IOS that is not affected by this issue. Additionally, restricting access to the Telnet service can help mitigate the risk.

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:<= 12.2\(15\)zj3

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

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. Check installed Cisco IOS version
    Use the command 'show version' in the device's command line interface
    Affected if the installed version is 12.2(15) or earlier
  2. Verify if Telnet is enabled
    Check the configuration with 'show running-config' and look for 'line vty' settings
    Affected if Telnet is configured and accessible
  3. Inspect for reverse Telnet configuration
    Review the configuration for any reverse Telnet settings
    Affected if reverse Telnet is configured and accessible

You are affected if your Cisco IOS version is 12.2(15) or earlier and Telnet or reverse Telnet is enabled.

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
Upgrade available Upgrade to a release after 12.2
Vendor patch www.kb.cert.org →
Interim mitigation

To remediate this vulnerability, it is recommended to upgrade to a later version of Cisco IOS that is not affected by this issue. Additionally, restricting access to the Telnet service can help mitigate the risk.

Fix this in iOS Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,690
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,304.

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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-2004-1464 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