Is CVE-2025-20311 in the CISA KEV catalog?

No. CVE-2025-20311 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-20311?

CVE-2025-20311 has a CVSS v3 base score of 7.4 (HIGH).

What is the EPSS score for CVE-2025-20311?

CVE-2025-20311 has an EPSS score of 0.19% (9th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2025-20311?

No published fix for CVE-2025-20311 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2025-20311

HIGH

7.4

CVSS v3

NVD

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.

CWE-19

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3 Vector

Exploitability

Attack VectorAdjacent

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.19%probability of exploitation in 30 days

9thpercentile

Low risk: more likely to be exploited than 9% of all known CVEs.

References

Other references1

sec.cloudapps.cisco.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-09-26.