CVE-2025-20311
HIGHDescription
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.
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CVSS v3.1 Score
7.4
HIGH
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness Type (CWE)
CWE-19
CWE-19
References
Frequently Asked Questions
What is 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 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. It has a CVSS v3.1 base score of 7.4 (HIGH).
How severe is CVE-2025-20311? +
CVE-2025-20311 has a CVSS v3.1 score of 7.4 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.
How do I check if I'm vulnerable to CVE-2025-20311? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.