TL;DR 📌

A denial of service vulnerability has been identified in Cisco IOS XE Software for Catalyst 9000 Series Switches. An unauthenticated, adjacent attacker can exploit this vulnerability by sending crafted Ethernet frames, causing an egress port to drop all outbound traffic. The highest CVSS score is 7.4 (High). Cisco has released fixed software, but no workarounds are available.

What happened 🕵️‍♂️

A vulnerability exists in the handling of certain Ethernet frames within Cisco IOS XE Software for Catalyst 9000 Series Switches. This flaw allows an unauthenticated, adjacent attacker to send crafted Ethernet frames, which can block an egress port, resulting in a denial of service (DoS) condition. Once exploited, the affected port will drop all outbound traffic, severely impacting network operations.