CVE-2026-20171

6.8 MEDIUM
Published: May 20, 2026 Modified: May 20, 2026
View on NVD

Description

A vulnerability in the Border Gateway Protocol (BGP) enforce-first-as feature of Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, remote attacker to trigger BGP peer flaps, resulting in a denial of service (DoS) condition. This vulnerability is due to incorrect parsing of a transitive BGP attribute. An attacker could exploit this vulnerability by sending a crafted BGP update through an established BGP peer session. If the update propagates to an affected device, it could cause the device to drop the BGP session and flap with the BGP peer that is forwarding this update, resulting in a DoS condition.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory

1 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.8 / 10.0
EPSS (Exploit Probability)
0.5%
37th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)