Is CVE-2026-20171 in the CISA KEV catalog?

No. CVE-2026-20171 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-20171?

CVE-2026-20171 has a CVSS v3 base score of 6.8 (MEDIUM).

What is the EPSS score for CVE-2026-20171?

CVE-2026-20171 has an EPSS score of 0.47% (37th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2026-20171?

No published fix for CVE-2026-20171 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-20171

MEDIUM

6.8

CVSS v3

NVD

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.

CWE-670

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H

Exploit Intelligence

0.47%probability of exploitation in 30 days

37thpercentile

Low risk: more likely to be exploited than 37% of all known CVEs.

References

Other references1

sec.cloudapps.cisco.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-20.