CVE-2025-20311

Published

24 September 2025

Modified

15 April 2026

CVSS Score v3.1 7.4

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Raw vector

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

EPSS Score 0.0020 10th percentile

Risk Priority 52 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2025-20311 is a high-severity an unspecified weakness vulnerability in Cisco IOS XE (inferred from references). Its CVSS base score is 7.4 (High).

Operationally, ranked at the 10th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2025-31032

Vulnerability Data

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.