Detections
Analytics
Cisco Nexus 3000 and 9000 Series Switches BGP DoS (cisco-sa-bgp-iefab-3hb2pwtx)
medium Nessus Plugin ID 317742
Synopsis
The remote device is missing a vendor-supplied security patchDescription
According to its self-reported version, Cisco NX-OS Software is affected by a vulnerability.- 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.
(CVE-2026-20171)
Please see the included Cisco BIDs and Cisco Security Advisory for more information.
Solution
Upgrade to the relevant fixed version referenced in Cisco bug ID CSCwr23951See Also
Plugin Details
Severity: Medium
ID: 317742
File Name: cisco-sa-bgp-iefab-3hb2pwtx.nasl
Version: 1.1
Type: Combined
Family: CISCO
Published: 5/29/2026
Updated: 5/29/2026
Supported Sensors: Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 5.2
CVSS v2
Risk Factor: Medium
Base Score: 5.4
Temporal Score: 4
Vector: CVSS2#AV:N/AC:H/Au:N/C:N/I:N/A:C
CVSS Score Source: CVE-2026-20171
CVSS v3
Risk Factor: Medium
Base Score: 6.8
Temporal Score: 5.9
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
CPE: cpe:/o:cisco:nx-os
Required KB Items: Host/Cisco/NX-OS/Version, Host/Cisco/NX-OS/Model, Host/Cisco/NX-OS/Device
Exploit Ease: No known exploits are available
Patch Publication Date: 5/20/2026
Vulnerability Publication Date: 5/20/2026
Reference Information
CVE: CVE-2026-20171