CVE-1999-1466: Cisco IOS

High severity, CVSS 7.5. EPSS: 2.3% chance of exploitation in the next 30 days.

Vulnerability in Cisco routers versions 8.2 through 9.1 allows remote attackers to bypass access control lists when extended IP access lists are used on certain interfaces, the IP route cache is enabled, and the access list uses the "established" keyword.

Affected products

• Cisco IOS: version 8.2 only; version 8.3 only; version 9.0 only; version 9.1 only

Published 1992-12-10. Last modified 2026-06-16.