CVE-2020-3221: Cisco IOS XE

High severity, CVSS 8.6. EPSS: 1.5% chance of exploitation in the next 30 days.

A vulnerability in the Flexible NetFlow Version 9 packet processor of Cisco IOS XE Software for Cisco Catalyst 9800 Series Wireless Controllers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper validation of parameters in a Flexible NetFlow Version 9 record. An attacker could exploit this vulnerability by sending a malformed Flexible NetFlow Version 9 packet to the Control and Provisioning of Wireless Access Points (CAPWAP) data port of an affected device. An exploit could allow the attacker to trigger an infinite loop, resulting in a process crash that would cause a reload of the device.

Affected products

• Cisco IOS XE: version 16.10.1 only; version 16.10.1a only; version 16.10.1b only; version 16.10.1e only; version 16.10.1s only; version 16.10.2 only; …

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