Product:
Cisco IOS XE Software
Summary
A vulnerability in the access control list programming of Cisco IOS XE Software for Cisco Catalyst 9500X and 9600X Series Switches could allow an unauthenticated, remote attacker to bypass a configured ACL on an affected device. This vulnerability is due to the flooding of traffic from an unlearned MAC address on a switch virtual interface that has an egress ACL applied. A successful exploit could allow the attacker to bypass an egress ACL on an affected device.
Details
| Severity | Base Score | CVE |
|---|---|---|
| MEDIUM | 5.3 | CVE-2025-20316 |
Exploitation
An attacker can exploit this vulnerability by causing the VLAN to flush its MAC address table, which can occur if the MAC address table is full. By flooding traffic from an unlearned MAC address on a switch virtual interface with an egress ACL, the attacker can bypass the configured access control list.
Affected Products
- Cisco Catalyst 9500X Series Switches
- Cisco Catalyst 9600X Series Switches
Mitigation
To mitigate this vulnerability, it is recommended to apply the latest software updates provided by Cisco for the affected products. Additionally, monitoring network traffic for unusual patterns and ensuring proper configuration of access control lists can help reduce the risk of exploitation.