Skip to main content

Cisco NX-OS CVE-2026-20171

| EUVD-2026-31135 MEDIUM
Always-Incorrect Control Flow Implementation (CWE-670)
2026-05-20 cisco GHSA-h75f-8f3x-9m8c
6.8
CVSS 3.1
Share

CVSS VectorNVD

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

1
Analysis Generated
May 20, 2026 - 17:32 vuln.today

DescriptionNVD

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.

AnalysisAI

BGP session flapping denial-of-service in Cisco NX-OS on Nexus 3000 and 9000 Series Switches exposes data-center routing infrastructure to disruption from unauthenticated remote attackers. The flaw resides in the enforce-first-as BGP feature, where incorrect parsing of a transitive BGP attribute causes an affected switch to drop its BGP peer session and enter a flap loop upon receiving a crafted BGP UPDATE message. …

Sign in for full analysis, threat intelligence, and remediation guidance.

Share

CVE-2026-20171 vulnerability details – vuln.today

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy