Cisco : Security Vulnerabilities, CVEs, Published In 2001 (Denial of service) CVSS score >= 7

Cisco VPN 3000 series concentrators before 2.5.2(F) allow remote attackers to cause a denial of service via a flood of invalid login requests to (1) the SSL service, or (2) the telnet service, which do not properly disconnect the user after several failed login attempts.

Memory leak in Cisco Catalyst 4000, 5000, and 6000 series switches allows remote attackers to cause a denial of service via a series of failed telnet authentication attempts.