CVE-2025-20311 - CVE House
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Status published High CVE-2025-20311

A vulnerability in the handling of certain Ethernet frames in...

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

References

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Affected Vendor

Affected Software

Cisco IOS XE Software
Vulnerable Versions:
16.6.1, 16.6.2, 16.6.3, 16.6.4, 16.6.5, 16.6.4a, 16.6.6, 16.6.7, 16.6.8, 16.6.9, 16.6.10, 16.7.1, 16.8.1, 16.8.1a, 16.8.1s, 16.9.1, 16.9.2, 16.9.1s, 16.9.3, 16.9.4, 16.9.5, 16.9.6, 16.9.7, 16.9.8, 16.10.1, 16.10.1s, 16.10.1e, 16.11.1, 16.11.1b, 16.11.1s, 16.12.1, 16.12.1s, 16.12.1c, 16.12.2, 16.12.3, 16.12.8, 16.12.2s, 16.12.4, 16.12.3s, 16.12.3a, 16.12.4a, 16.12.5, 16.12.6, 16.12.5b, 16.12.6a, 16.12.7, 16.12.14, 17.1.1, 17.1.1s, 17.1.1t, 17.1.3, 17.2.1, 17.2.1a, 17.3.1, 17.3.2, 17.3.3, 17.3.2a, 17.3.4, 17.3.5, 17.3.6, 17.3.4b, 17.3.7, 17.3.8, 17.3.8a, 17.4.1, 17.5.1, 17.6.1, 17.6.2, 17.6.3, 17.6.1y, 17.6.4, 17.6.5, 17.6.6, 17.6.6a, 17.6.5a, 17.6.7, 17.6.8, 17.7.1, 17.10.1, 17.10.1b, 17.8.1, 17.9.1, 17.9.2, 17.9.3, 17.9.4, 17.9.5, 17.9.4a, 17.9.6, 17.9.6a, 17.11.1, 17.12.1, 17.12.2, 17.12.3, 17.12.4, 17.12.1z3, 17.13.1, 17.14.1, 17.11.99SW, 17.15.1, 17.15.2, 17.15.2a, 17.15.2b, 17.16.1

Timeline

Official Publish: September 24th, 2025
Last Modified: September 30th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Weaknesses (CWE)

CWE-19

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.