CVE-2005-1021: Cisco IOS

High severity, CVSS 7.1. EPSS: 1.8% chance of exploitation in the next 30 days.

Memory leak in Secure Shell (SSH) in Cisco IOS 12.0 through 12.3, when authenticating against a TACACS+ server, allows remote attackers to cause a denial of service (memory consumption) via an incorrect username or password.

Affected products

• Cisco IOS: version 12.0s only; version 12.0sx only; version 12.1ax only; version 12.1az only; version 12.1db only; version 12.1dc only; …

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