CVE-2004-0551

What it is

Cisco CatOS 5.x before 5.5(20) through 8.x before 8.2(2) and 8.3(2)GLX, as used in Catalyst switches, allows remote attackers to cause a denial of service (system crash and reload) by sending invalid packets instead of the final ACK portion of the three-way handshake to the (1) Telnet, (2) HTTP, or (3) SSH services, aka "TCP-ACK DoS attack."

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

3.1% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2004-08-06 04:00 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-16 22:05 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 3.1% in the next 30 days (EPSS).
• Severity: 5.0 MEDIUM (CVSS).
• Fix: none linked yet, which raises it.

Details

Published

2004-08-06 04:00 UTC

Last modified

2026-06-16 22:05 UTC

Exploit probability

3.1% · EPSS, next 30 days

Record status

Modified

Affected

• Cisco Catos 2.1\(1\)
• Cisco Catos 2.1\(2\)
• Cisco Catos 2.1\(3\)
• Cisco Catos 2.1\(4\)
• Cisco Catos 2.1\(5\)
• Cisco Catos 2.1\(6\)
• Cisco Catos 2.1\(7\)
• Cisco Catos 2.1\(8\)

Attack profile CVSS 2.0 · 5.0

Attack vector

Network

Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Partial

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2004-0551.md and follow it. Check whether this project is affected by CVE-2004-0551. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge