CVE-2021-34696: Cisco IOS XE

Medium severity, CVSS 5.8. EPSS: 1% chance of exploitation in the next 30 days.

A vulnerability in the access control list (ACL) programming of Cisco ASR 900 and ASR 920 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to bypass a configured ACL. This vulnerability is due to incorrect programming of hardware when an ACL is configured using a method other than the configuration CLI. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to bypass an ACL on the affected device.

Affected products

• Cisco IOS XE: up to and including 17.3.2

Published 2021-09-23. Last modified 2026-06-17.