CVE-2026-20171
Last modified
CVE-2026-20171 is a medium-severity vulnerability rated 6.8/10 on the CVSS scale. 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. EPSS estimates a 0.47% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness Enumeration
Affected Software
Source: CNA advisory (CVE.org). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| 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) |
References
Timeline
- Published
- Last Modified
- Status
- Awaiting Analysis
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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