TI-2026-16379 Aliases CVE-2026-20171 GHSA-h75f-8f3x-9m8c

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

LOW 30CWE-670Published 2026-05-20 · Updated 2026-05-20

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Impact type: —
Confidentiality · integrity · availability: None · None · High
Fix status: No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

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 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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00467 40th percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Cisco	Cisco NX-OS Software	10.2(1); 10.2(1q); 10.2(2); 10.2(3); 10.2(3t); 10.2(2a); 10.3(1); 10.2(4); 10.3(2); 10.3(3); 10.2(5); 10.2(3v); 10.4(1); 10.3(99w); 10.2(6); 10.3(3w); 10.3(99x); 10.3(3o); 10.3(4); 10.3(3p); 10.3(4a); 10.4(2); 10.3(3q); 10.3(5); 10.2(7); 10.4(3); 10.3(3x); 10.3(4g); 10.5(1); 10.2(8); 10.3(3r); 10.3(6); 10.4(4); 10.3(4h); 10.5(2); 10.3(7); 10.4(5); 10.5(3); 10.2(9); 10.4(4g); 10.6(1); 10.5(3t); 10.3(8); 10.4(6); 10.5(3s); 10.5(3e); 10.5(3o); 10.6(1s); 10.5(3p)	—	No fix listed	CNA

Cisco NX-OS Software VendorCisco Affected 10.2(1); 10.2(1q); 10.2(2); 10.2(3); 10.2(3t); 10.2(2a); 10.3(1); 10.2(4); 10.3(2); 10.3(3); 10.2(5); 10.2(3v); 10.4(1); 10.3(99w); 10.2(6); 10.3(3w); 10.3(99x); 10.3(3o); 10.3(4); 10.3(3p); 10.3(4a); 10.4(2); 10.3(3q); 10.3(5); 10.2(7); 10.4(3); 10.3(3x); 10.3(4g); 10.5(1); 10.2(8); 10.3(3r); 10.3(6); 10.4(4); 10.3(4h); 10.5(2); 10.3(7); 10.4(5); 10.5(3); 10.2(9); 10.4(4g); 10.6(1); 10.5(3t); 10.3(8); 10.4(6); 10.5(3s); 10.5(3e); 10.5(3o); 10.6(1s); 10.5(3p) Fixed in — No fix listed CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:o:cisco:nx-os::::::::	—	—	Cisco

cpe:2.3:o:cisco:nx-os:*:*:*:*:*:*:*:* Versions — — ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2026-20171
2026-10-03 Alias added: GHSA-h75f-8f3x-9m8c

References

Other 1

cisco-sa-bgp-iefab-3hb2pwtx

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Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences