CVE-2025-20311

HIGH

7.4

CVSS Score

Published: September 24, 2025 at 05:12 PM UTC

Updated: September 26, 2026 at 12:27 AM UTC

56 products affected across 1 vendorIOS XeCatalyst 9300Catalyst 9300-48P-A

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Severity

HIGH7.4

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

IOS Xe · Cisco

95%

cisco-catalyst-9200 (environment) · cisco-catalyst-9200cx (environment) · cisco-catalyst-9200l (environment) · cisco-catalyst-9300 (environment) · cisco-catalyst-9300-24p-a (environment) · cisco-catalyst-9300-24p-e (environment) · cisco-catalyst-9300-24s-a (environment) · cisco-catalyst-9300-24s-e (environment) · cisco-catalyst-9300-24t-a (environment) · cisco-catalyst-9300-24t-e (environment) · cisco-catalyst-9300-24u-a (environment) · cisco-catalyst-9300-24u-e (environment) · cisco-catalyst-9300-24ux-a (environment) · cisco-catalyst-9300-24ux-e (environment) · cisco-catalyst-9300-48p-a (environment) · cisco-catalyst-9300-48p-e (environment) · cisco-catalyst-9300-48s-a (environment) · cisco-catalyst-9300-48s-e (environment) · cisco-catalyst-9300-48t-a (environment) · cisco-catalyst-9300-48t-e (environment) · cisco-catalyst-9300-48u-a (environment) · cisco-catalyst-9300-48u-e (environment) · cisco-catalyst-9300-48un-a (environment) · cisco-catalyst-9300-48un-e (environment) · cisco-catalyst-9300-48uxm-a (environment) · cisco-catalyst-9300-48uxm-e (environment) · cisco-catalyst-9300l (environment) · cisco-catalyst-9300l-24p-4g-a (environment) · cisco-catalyst-9300l-24p-4g-e (environment) · cisco-catalyst-9300l-24p-4x-a (environment) · cisco-catalyst-9300l-24p-4x-e (environment) · cisco-catalyst-9300l-24t-4g-a (environment) · cisco-catalyst-9300l-24t-4g-e (environment) · cisco-catalyst-9300l-24t-4x-a (environment) · cisco-catalyst-9300l-24t-4x-e (environment) · cisco-catalyst-9300l-48p-4g-a (environment) · cisco-catalyst-9300l-48p-4g-e (environment) · cisco-catalyst-9300l-48p-4x-a (environment) · cisco-catalyst-9300l-48p-4x-e (environment) · cisco-catalyst-9300l-48t-4g-a (environment) · cisco-catalyst-9300l-48t-4g-e (environment) · cisco-catalyst-9300l-48t-4x-a (environment) · cisco-catalyst-9300l-48t-4x-e (environment) · cisco-catalyst-9300l-stack (environment) · cisco-catalyst-9300lm (environment) · cisco-catalyst-9300x (environment) · cisco-catalyst-9400 (environment) · cisco-catalyst-9400-supervisor-engine-1 (environment) · cisco-catalyst-9407r (environment) · cisco-catalyst-9410r (environment) · cisco-catalyst-9500 (environment) · cisco-catalyst-9500h (environment) · cisco-catalyst-9600 (environment) · cisco-catalyst-9600-supervisor-engine-1 (environment) · cisco-catalyst-9600x (environment)

Catalyst 9200 · Ciscodevice

80%

All versions

Catalyst 9200Cx · Ciscodevice

80%

All versions

Catalyst 9200L · Ciscodevice

80%

All versions

Catalyst 9300 · Ciscodevice

80%

All versions