Access Control Bypass in Cisco Catalyst 9500X and 9600X Series Switches

CVE-2025-20316

What is CVE-2025-20316?

A vulnerability exists in the access control list (ACL) programming of Cisco IOS XE Software that affects Catalyst 9500X and 9600X Series Switches. This vulnerability allows a remote, unauthenticated attacker to bypass configured ACLs by flooding traffic from an unlearned MAC address on a switch virtual interface (SVI) experiencing an egress ACL. Potential exploitation occurs when the VLAN's MAC address table is flushed or becomes full, enabling an attacker to circumvent security controls.

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