CVE-2025-20311
Medium
Elevated severity or exploit probability.
CVSS base
7.4
HIGH
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS — probability of exploitation (30 days)
0.2%
10.4th percentile
CISA KEV
Not listed
Weakness / dates
CWE-19
Published 2025-09-24 · modified 2026-09-18
CVSS breakdown
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
| Attack Vector | A | Adjacent |
| Attack Complexity | L | Low |
| Privileges Required | N | None |
| User Interaction | N | None |
| Scope | C | Changed |
| Confidentiality | N | None |
| Integrity | N | None |
| Availability | H | High |
Timeline
- 2025-09-24 — Published (NVD)
- 2026-09-18 — Last modified (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.