Vulnerability Database

383,371

Total vulnerabilities in the database

CVE-2004-0551 — cisco / catalyst_2980g-a

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."

  • Published: Aug 6, 2004
  • Updated: Sep 13, 2026
  • CVE: CVE-2004-0551
  • Severity: Medium
  • Exploit:
  • CISA KEV:

CVSS v2:

  • Severity: Medium
  • Score: 5
  • AV:N/AC:L/Au:N/C:N/I:N/A:P

No CWE or OWASP classifications available.

Software Affected versions
cisco / catalyst_2980g-a All versions
cisco / catalyst_2926 All versions
cisco / catalyst_4500 All versions
cisco / catalyst_5000 All versions
cisco / catalyst_2901 All versions
cisco / catalyst_4506 All versions
cisco / catalyst_4912g All versions
cisco / catalyst_2926f All versions
cisco / catalyst_2926gl All versions
cisco / catalyst_2948 All versions
cisco / catalyst_2902 All versions
cisco / catalyst_2980g All versions
cisco / catalyst_4510r All versions
cisco / catalyst_2948g-l3 All versions
cisco / catalyst_4503 All versions
cisco / catalyst_2926gs All versions
cisco / catalyst_2948-ge-tx All versions
cisco / catalyst_4000 All versions
cisco / catalyst_2926t All versions
cisco / catalyst_4507r All versions
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)
cisco / catos = 2.1(9)
cisco / catos = 2.1(10)
cisco / catos = 2.1(11)
cisco / catos = 2.1(12)
cisco / catos = 2.2(1)
cisco / catos = 2.2(2)
cisco / catos = 2.3(1)
cisco / catos = 2.4(1)
cisco / catos = 2.4(2)
cisco / catos = 2.4(3)
cisco / catos = 2.4(4)
cisco / catos = 2.4(5)
cisco / catos = 2.4(5a)
cisco / catos = 3.0(7)
cisco / catos = 3.1(1)
cisco / catos = 3.1(2)
cisco / catos = 3.1(2a)
cisco / catos = 3.2(1)
cisco / catos = 3.2(1b)
cisco / catos = 3.2(2)
cisco / catos = 3.2(3)
cisco / catos = 3.2(4)
cisco / catos = 3.2(5)
cisco / catos = 3.2(6)
cisco / catos = 3.2(7)
cisco / catos = 3.2(8)gdr
cisco / catos = 4.1(1)
cisco / catos = 4.1(2)
cisco / catos = 4.1(3)
cisco / catos = 4.2(1)
cisco / catos = 4.2(2)
cisco / catos = 4.3(1a)
cisco / catos = 4.4(1)
cisco / catos = 4.5(1)
cisco / catos = 4.5(2)
cisco / catos = 4.5(3)
cisco / catos = 4.5(4)
cisco / catos = 4.5(5)
cisco / catos = 4.5(6)
cisco / catos = 4.5(6a)
cisco / catos = 4.5(7)
cisco / catos = 4.5(8)
cisco / catos = 4.5(9)
cisco / catos = 4.5(10)
cisco / catos = 4.5(11)
cisco / catos = 4.5(12)
cisco / catos = 4.5(12a)
cisco / catos = 4.5(13)
cisco / catos = 4.5(13a)
cisco / catos = 4.5(14)
cisco / catos = 5.1(1)
cisco / catos = 5.1(1)csx
cisco / catos = 5.1(1a)
cisco / catos = 5.1(1a)csx
cisco / catos = 5.1(2a)
cisco / catos = 5.1(2b)
cisco / catos = 5.2(1)
cisco / catos = 5.2(1)csx
cisco / catos = 5.2(2)
cisco / catos = 5.2(2)csx
cisco / catos = 5.2(3)
cisco / catos = 5.2(3)csx
cisco / catos = 5.2(3a)csx
cisco / catos = 5.2(4)
cisco / catos = 5.2(5)
cisco / catos = 5.2(6)
cisco / catos = 5.2(7)
cisco / catos = 5.2(7a)
cisco / catos = 5.3(1a)csx
cisco / catos = 5.3(2)csx
cisco / catos = 5.3(3)csx
cisco / catos = 5.3(4)csx
cisco / catos = 5.3(5)csx
cisco / catos = 5.3(5a)csx
cisco / catos = 5.3(6)csx
cisco / catos = 5.3(6a)csx
cisco / catos = 5.4
cisco / catos = 5.4(1)
cisco / catos = 5.4(1)deferred
cisco / catos = 5.4(2)
cisco / catos = 5.4(2a)
cisco / catos = 5.4(3)
cisco / catos = 5.4(4)
cisco / catos = 5.4(4a)
cisco / catos = 5.5
cisco / catos = 5.5(1)
cisco / catos = 5.5(1a)
cisco / catos = 5.5(2)
cisco / catos = 5.5(3)
cisco / catos = 5.5(4)
cisco / catos = 5.5(4a)
cisco / catos = 5.5(4b)
cisco / catos = 5.5(5)
cisco / catos = 5.5(6)
cisco / catos = 5.5(6a)
cisco / catos = 5.5(7)
cisco / catos = 5.5(7a)
cisco / catos = 5.5(8)
cisco / catos = 5.5(8a)
cisco / catos = 5.5(8a)cv
cisco / catos = 5.5(9)
cisco / catos = 5.5(10)
cisco / catos = 5.5(10a)
cisco / catos = 5.5(11)
cisco / catos = 5.5(11a)
cisco / catos = 5.5(12)
cisco / catos = 5.5(12a)
cisco / catos = 5.5(13)
cisco / catos = 5.5(13.5)
cisco / catos = 5.5(13a)
cisco / catos = 5.5(14)
cisco / catos = 5.5(15)
cisco / catos = 5.5(16)
cisco / catos = 5.5(16.2)
cisco / catos = 5.5(17)
cisco / catos = 5.5(18)
cisco / catos = 5.5(19)
cisco / catos = 6.1
cisco / catos = 6.1(1)
cisco / catos = 6.1(1a)
cisco / catos = 6.1(1b)
cisco / catos = 6.1(1c)
cisco / catos = 6.1(1d)
cisco / catos = 6.1(1e)
cisco / catos = 6.1(2)
cisco / catos = 6.1(2a)
cisco / catos = 6.1(3)
cisco / catos = 6.1(3a)
cisco / catos = 6.1(4)
cisco / catos = 6.1(4b)
cisco / catos = 6.2(1)
cisco / catos = 6.2(1a)
cisco / catos = 6.2(2)
cisco / catos = 6.2(2a)
cisco / catos = 6.2(3)
cisco / catos = 6.2(3a)
cisco / catos = 6.3(1)
cisco / catos = 6.3(1a)
cisco / catos = 6.3(2)
cisco / catos = 6.3(2a)
cisco / catos = 6.3(3)
cisco / catos = 6.3(3)x
cisco / catos = 6.3(3)x1
cisco / catos = 6.3(3a)
cisco / catos = 6.3(4)
cisco / catos = 6.3(4a)
cisco / catos = 6.3(5)
cisco / catos = 6.3(5.10)
cisco / catos = 6.3(6)
cisco / catos = 6.3(7)
cisco / catos = 6.3(8)
cisco / catos = 6.3(8.3)
cisco / catos = 6.3(9)
cisco / catos = 6.3(10)
cisco / catos = 6.4(1)
cisco / catos = 6.4(2)
cisco / catos = 6.4(3)
cisco / catos = 6.4(4a)
cisco / catos = 6.4(5)
cisco / catos = 6.4(6)
cisco / catos = 6.4(7)
cisco / catos = 6.4(8)
cisco / catos = 7.1(1)
cisco / catos = 7.1(1a)
cisco / catos = 7.1(2)
cisco / catos = 7.1(2a)
cisco / catos = 7.2(0.65)
cisco / catos = 7.2(1)
cisco / catos = 7.2(2)
cisco / catos = 7.3
cisco / catos = 7.3(1)
cisco / catos = 7.3(2)
cisco / catos = 7.4
cisco / catos = 7.4(0.2)clr
cisco / catos = 7.4(0.63)
cisco / catos = 7.4(1)
cisco / catos = 7.4(2)
cisco / catos = 7.4(3)
cisco / catos = 7.5
cisco / catos = 7.5(1)
cisco / catos = 7.6
cisco / catos = 7.6(1)
cisco / catos = 7.6(2)
cisco / catos = 7.6(3)
cisco / catos = 7.6(4)
cisco / catos = 7.6(5)
cisco / catos = 8.1
cisco / catos = 8.1(2)
cisco / catos = 8.1(3)
cisco / catos = 8.2
cisco / catos = 8.2(1)
cisco / catos = 8.3(1)glx
cisco / catos = 8.3glx
cisco / catalyst_6000_ws-svc-nam-1 = 2.2(1a)
cisco / catalyst_6000_ws-svc-nam-1 = 3.1(1a)
cisco / catalyst_6000_ws-svc-nam-2 = 2.2(1a)
cisco / catalyst_6000_ws-svc-nam-2 = 3.1(1a)
cisco / catalyst_6000_ws-x6380-nam = 2.1(2)
cisco / catalyst_6000_ws-x6380-nam = 3.1(1a)
cisco / catos = 4.5(4b)
cisco / catos = 4.5.10
cisco / catos = 5.1
cisco / catos = 5.2
cisco / catos = 5.2(1a)
cisco / catos = 5.3(1)csx
cisco / catos = 6.1(2.13)
cisco / catos = 6.2(0.110)
cisco / catos = 6.2(0.111)
cisco / catos = 6.3(0.7)pan
cisco / catos = 7.1

Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.