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Optical Networking Systems SoftwareApplication · Cisco

CVE-2004-1435

MEDIUM · 5.0 CVSS v2.0 Published 2004-12-31
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
Multiple versions of Cisco ONS 15327, ONS 15454, and ONS 15454 SDH, including 4.6(0) and 4.6(1), 4.5(x), 4.1(0) to 4.1(3), 4.0(0) to 4.0(2), and earlier versions, allows remote attackers to cause a denial of service (control card reset) via a large number of TCP connections with an invalid response instead of the final ACK (TCP-ACK).

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 confidence

This vulnerability in Cisco ONS 15327, ONS 15454, and ONS 15454 SDH optical networking platforms allows remote attackers to cause denial of service by sending a large volume of TCP connection attempts that never complete the three-way handshake (missing final ACK). The incomplete TCP connections exhaust resources or trigger a fault condition resulting in control card reset.

MitigationApply vendor firmware updates if available; given the age of affected versions (2004-era), these platforms may be end-of-life requiring replacement. Alternatively, implement network segmentation and ACLs to restrict access to management TCP ports or deploy IDS/IPS to detect and block malformed TCP connection patterns.

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
Optical Networking Systems SoftwareApplication
Affected:= 1.0= 1.1= 1.1\(0\)= 1.1\(1\)= 1.3\(0\)= 2.3\(5\)= 3.0= 3.1.0= 3.2= 3.2.0= 3.3.0= 3.4.0

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 the Cisco ONS platform model
    Use CLI command 'show hardware' or check the physical label on the device to determine if the model is ONS 15327, ONS 15454, or ONS 15454 SDH
    Affected if The device model is one of these three platforms
  2. Check the installed software version
    Use CLI command 'show version' or 'show software version' to retrieve the Cisco Optical Networking Systems Software version
    Affected if The version matches any of the following: 1.0, 1.1, 1.1(0), 1.1(1), 1.3(0), 2.3(5), 3.0, 3.1.0, 3.2, 3.2.0, 3.3.0, or 3.4.0
  3. Verify management TCP port exposure
    Review network configuration using 'show ip interface' or check firewall/ACL rules to determine if TCP management ports (typically 23/telnet, 80/http, or 443/https) are accessible from untrusted networks
    Affected if Management ports are reachable from outside the trusted management network
  4. Check for incomplete TCP connections
    Use 'show tcp' or 'show connections' CLI command to view active TCP sessions and look for connections in SYN_RCVD or SYN_SENT states that remain stuck
    Affected if A large number of incomplete TCP connections are present in the connection table
  5. Review system logs for control card resets
    Examine logs using 'show log' or 'show alarm history' for messages indicating control card resets or system reloads
    Affected if Logs show unexpected control card resets or resource exhaustion errors correlating with TCP connection activity

You are affected if your device is an ONS 15327, 15454, or 15454 SDH running any of the listed versions and management TCP ports are exposed to untrusted networks.

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

Apply vendor firmware updates if available; given the age of affected versions (2004-era), these platforms may be end-of-life requiring replacement. Alternatively, implement network segmentation and ACLs to restrict access to management TCP ports or deploy IDS/IPS to detect and block malformed TCP connection patterns.

Fix this in Optical Networking Systems Software Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2004-1435 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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