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

Severity
High 7.4
CVSS 3.1
Exploited
Not listed
EPSS
0.002
8.6th percentile
Discovered by
Vendor
Published by the vendor
Published
Sep 24, 2025
Assigned by cisco

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 affected versions (1)
  • Cisco · Cisco IOS XE Software