CVE-2025-20311: High severity Cisco IOS XE Software for Catalyst 9000 Series Switches vulnerability
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 Software
Event History
Frequently Asked Questions
What is the severity of CVE-2025-20311?
CVE-2025-20311 has a high severity level due to its potential impact on network availability.
How do I fix CVE-2025-20311?
To fix CVE-2025-20311, you should update your Cisco IOS XE Software for Catalyst 9000 Series Switches to the latest version provided by Cisco.
Who is affected by CVE-2025-20311?
CVE-2025-20311 affects Cisco IOS XE Software for the Catalyst 9000 Series Switches.
What can an attacker do with CVE-2025-20311?
An attacker exploiting CVE-2025-20311 can block an egress port, causing all outbound traffic to drop.
Is CVE-2025-20311 remotely exploitable?
CVE-2025-20311 is not remotely exploitable as it requires an adjacent attacker to exploit the vulnerability.