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CVE-2025-20311

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CVE-2025-20311

Published: Sep 24, 2025

Modified: Sep 30, 2025

PUBLISHED

CVSS v3.1

7.4

HIGH

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.

VendorProductVersions

Cisco

Cisco IOS XE Software

affected
16.6.1
affected
16.6.2
affected
16.6.3
affected
16.6.4
affected
16.6.5

+98 more versions

Weaknesses (CWE)

CWE-19

CVSS v3.1 Details

CVSS v3.1 Vector

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

High

References

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