Vulnerability in Cisco iOS Xe Software
CVE-2025-20311
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.002 (9.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 9th percentile — 9.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Cisco iOS Xe Software — versions 16.6.1, 16.6.2, 16.6.3
- Cisco iOS Xe — versions 16.10.1, 16.10.1e, 16.10.1s
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2025-20311?
- CVE-2025-20311 is a high-severity vulnerability in Cisco iOS Xe Software, classified under CWE-19. CVSS score: 7.4/10. Published 2025-09-24.
- How severe is CVE-2025-20311?
- High severity. CVSS v3 base score is 7.4 out of 10.