CVE-2026-20171
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…
Does this matter?
Lower severity and a low EPSS score (0.47%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 6.8 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
- EPSS
- 0.47% probability · 39th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-670
- Source
- psirt@cisco.com
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.