CVE-2026-20171
published 2026-05-20CVE-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…
PriorityP339medium6.8CVSS 3.1
AVNACHPRNUINSCCNINAH
EPSS
0.47%
37.6th percentile
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.
Affected
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VulDB
Cisco NX-OS Software up to 10.6(1s) BGP Enforce-First-As Feature control flow (cisco-sa-bgp-iefab-3hb2pwtx)
vuldb·2026-05-20·CVSS 6.8
CVE-2026-20171 [MEDIUM] Cisco NX-OS Software up to 10.6(1s) BGP Enforce-First-As Feature control flow (cisco-sa-bgp-iefab-3hb2pwtx)
A vulnerability has been found in Cisco NX-OS Software and classified as problematic. The impacted element is an unknown function of the component BGP Enforce-First-As Feature. Performing a manipulation results in incorrect control flow.
This vulnerability is cataloged as CVE-2026-20171. It is possible to initiate the attack remotely. There is no exploit available.
The affected component should be upgraded.
GHSA
GHSA-h75f-8f3x-9m8c: A vulnerability in the Border Gateway Protocol (BGP) enforce-first-as feature of Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches
ghsa_unreviewed·2026-05-20
CVE-2026-20171 [MEDIUM] CWE-670 GHSA-h75f-8f3x-9m8c: A vulnerability in the Border Gateway Protocol (BGP) enforce-first-as feature of Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches
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.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-05-20
Published