Cisco Nexus 3000 and 9000 Series Switches Border Gateway Protocol Denial of Service Vulnerability — CISCO-SA-BGP-IEFAB-3HB2PWTX

Summary

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…

Timeline

Published by source

2026-05-20

Risk context

• Reported severity or threat level: medium.
• Review exposure for the affected product or family: Cisco Nexus 3000 and 9000 Series Switches Border Gateway Protocol Denial of Service.

Product

Cisco Nexus 3000 and 9000 Series Switches Border Gateway Protocol Denial of Service

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

CISCO-SA-BGP-IEFAB-3HB2PWTX

Source

Cisco

Vendor

Cisco

Published by source

2026-05-20

Last source activity

2026-05-20

Additional identifiers

CVE-2026-20171

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.