CVE-2026-20171Cisco Nexus 3000 and 9000 Series Border Gateway Protocol Denial of Service Vulnerability
Updated under an hour ago ()
Does this affect you?
It affects Cisco NX-OS Software. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
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
- 6.8 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
- Weakness (CWE)
- CWE-670
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- cisco
- NVD analysis
- Awaiting Analysis
- Record last updated
- May 20, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Cisco Cisco NX-OS Software cisco:nx_os_software (from the name) | 10.2(1); 10.2(1q); 10.2(2); 10.2(3); 10.2(3t); 10.2(2a); 10.3(1); 10.2(4); and 41 more ranges | CNA record |
References
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-bgp-iefab-3hb2pwtx
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.