CVE-2025-20311
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 becom
Description
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.
Weakness: CWE-19
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco IOS XE Software | Routing & Switching | cna-assigner |
Vendor-reported products (1)
- Cisco · Cisco IOS XE Software
Vendor advisory
Cisco IOS XE Software for Catalyst 9000 Series Switches Denial of Service Vulnerability
Cisco’s rating: High (advisory CVSS 7.4) · Published Sep 24, 2025 · updated Sep 30, 2025 (revision 1.1)
Bug ID: CSCwn45401
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from