CVE-1999-0160: Cisco IOS

High severity, CVSS 7.5. EPSS: 1.2% chance of exploitation in the next 30 days.

Some classic Cisco IOS devices have a vulnerability in the PPP CHAP authentication to establish unauthorized PPP connections.

Affected products

• Cisco IOS: version 4.1 only; version 9.1 only; version 10.3 only; version 11.0 only; version 11.1 only; version 11.2 only; …

Published 1997-10-01. Last modified 2026-06-16.