CVE-2004-0551: Cisco Catalyst 2901

Medium severity, CVSS 5.0. EPSS: 3.1% chance of exploitation in the next 30 days.

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."

Affected products

• Cisco Catalyst 2901: any version
• Cisco Catalyst 2902: any version
• Cisco Catalyst 2926: any version
• Cisco Catalyst 2926f: any version
• Cisco Catalyst 2926gl: any version
• Cisco Catalyst 2926gs: any version
• Cisco Catalyst 2926t: any version
• Cisco Catalyst 2948: any version
• Cisco Catalyst 2948-Ge-Tx: any version
• Cisco Catalyst 2948g-l3: any version
• Cisco Catalyst 2980g: any version
• Cisco Catalyst 2980g-A: any version
• Cisco Catalyst 4000: any version
• Cisco Catalyst 4500: any version
• Cisco Catalyst 4503: any version
• Cisco Catalyst 4506: any version
• Cisco Catalyst 4507r: any version
• Cisco Catalyst 4510r: any version
• Cisco Catalyst 4912g: any version
• Cisco Catalyst 5000: any version
• Cisco Catalyst 6000 Ws-Svc-Nam-1: version 2.2(1a) only; version 3.1(1a) only
• Cisco Catalyst 6000 Ws-Svc-Nam-2: version 2.2(1a) only; version 3.1(1a) only
• Cisco Catalyst 6000 Ws-x6380-Nam: version 2.1(2) only; version 3.1(1a) only
• Cisco Catos: version 2.1(1) only; version 2.1(2) only; version 2.1(3) only; version 2.1(4) only; version 2.1(5) only; version 2.1(6) only; …

Published 2004-08-06. Last modified 2026-06-16.