What happened
A vulnerability in the handling of certain Ethernet frames in Cisco IOS XE Software for Catalyst 9000 Series Switches could allow an unauthenticated, adjacent attacker to cause an egress port to become blocked and drop all outbound traffic. This vulnerability is due to improper handling of crafted Ethernet frames. An attacker could exploit this vulnerability by sending crafted Ethernet frames through an affected switch. A successful exploit could allow the attacker to cause the egress port to which the crafted frame is forwarded to start dropping all frames, resulting in a denial of service (DoS) condition.
Affected versions
Cisco IOS XE Software: 16.6.1; 16.6.2; 16.6.3; 16.6.4; 16.6.5; 16.6.4a; 16.6.6; 16.6.7; 16.6.8; 16.6.9; 16.6.10; 16.7.1; 16.8.1; 16.8.1a; 16.8.1s; 16.9.1; 16.9.2; 16.9.1s; 16.9.3; 16.9.4; 16.9.5; 16.9.6; 16.9.7; 16.9.8; 16.10.1; 16.10.1s; 16.10.1e; 16.11.1; 16.11.1b; 16.11.1s; 16.12.1; 16.12.1s; 16.12.1c; 16.12.2; 16.12.3; 16.12.8; 16.12.2s; 16.12.4; 16.12.3s; 16.12.3a; 16.12.4a; 16.12.5; 16.12.6; 16.12.5b; 16.12.6a; 16.12.7; 16.12.14; 17.1.1; 17.1.1s; 17.1.1t; 17.1.3; 17.2.1; 17.2.1a; 17.3.1; 17.3.2; 17.3.3; 17.3.2a; 17.3.4; 17.3.5; 17.3.6; 17.3.4b; 17.3.7; 17.3.8; 17.3.8a; 17.4.1; 17.5.1; 17.6.1; 17.6.2; 17.6.3; 17.6.1y; 17.6.4; 17.6.5; 17.6.6; 17.6.6a; 17.6.5a; 17.6.7; 17.6.8; 17.7.1; 17.10.1; 17.10.1b; 17.8.1; 17.9.1; 17.9.2; 17.9.3; 17.9.4; 17.9.5; 17.9.4a; 17.9.6; 17.9.6a; 17.11.1; 17.12.1; 17.12.2; 17.12.3; 17.12.4; 17.12.1z3; 17.13.1; 17.14.1; 17.11.99SW; 17.15.1; 17.15.2; 17.15.2a; 17.15.2b; 17.16.1 Fixed: See vendor advisory.
Why it matters
Review the vendor advisory and exposure of the affected product to determine operational impact.
Detection & mitigation
- Apply vendor-provided updates or mitigations.
- Review affected product exposure and access logs.
Public PoC references
No public PoC reference has passed the current publication threshold.