CVE-2020-3231: Cisco IOS

Medium severity, CVSS 4.7. EPSS: 0.5% chance of exploitation in the next 30 days.

A vulnerability in the 802.1X feature of Cisco Catalyst 2960-L Series Switches and Cisco Catalyst CDB-8P Switches could allow an unauthenticated, adjacent attacker to forward broadcast traffic before being authenticated on the port. The vulnerability exists because broadcast traffic that is received on the 802.1X-enabled port is mishandled. An attacker could exploit this vulnerability by sending broadcast traffic on the port before being authenticated. A successful exploit could allow the attacker to send and receive broadcast traffic on the 802.1X-enabled port before authentication.

Affected products

• Cisco IOS: version 15.2(5)e2 only; version 15.2(5)ex only; version 15.2(5a)e only; version 15.2(5b)e only; version 15.2(5c)e only; version 15.2(6)e only; …

Published 2020-06-03. Last modified 2026-06-17.