CVE-2005-1020: Cisco IOS

High severity, CVSS 7.1. EPSS: 1.7% chance of exploitation in the next 30 days.

Secure Shell (SSH) 2 in Cisco IOS 12.0 through 12.3 allows remote attackers to cause a denial of service (device reload) (1) via a username that contains a domain name when using a TACACS+ server to authenticate, (2) when a new SSH session is in the login phase and a currently logged in user issues a send command, or (3) when IOS is logging messages and an SSH session is terminated while the server is sending data.

Affected products

• Cisco IOS: version 12.0 only; version 12.0(23)s4 only; version 12.0(23)s5 only; version 12.0(24)s1 only; version 12.0(24)s4 only; version 12.0(24)s5 only; …

Published 2005-05-02. Last modified 2026-06-16.