Cisco Nexus 3000- und 9000-Switches im Standalone-NX-OS-Modus: Schwachstelle ermöglicht Denial of Service
WID-SEC-2026-1622 · first 21.05.2026 · updated 21.05.2026 · CVSS 6,8
What it is about
Bei der Cisco Nexus Serie handelt es sich um modulare Switching-Systeme der Data Center-Klasse. Cisco NX-OS ist ein Data Center Netzwerk-Betriebssystem für virtualisierte Rechenzentren. NX-OS wurde für Ethernet Switches der Nexus Serie und Fibre Channel Storage Area Network Swiches der MDS Serie entwickelt. Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Cisco Nexus 3000- und Nexus 9000-Switch-Serie im Standalone-NX-OS-Modus ausnutzen, um einen Denial of Service Angriff durchzuführen.
Under what conditions?
Over the network and without logging in. This is the most dangerous combination: attackers can scan reachable devices automatically.
What can happen in the worst case
An attacker could use the vulnerability to
- einen Denial of Service Angriff durchzuführen
Am I affected?
Affected according to the BSI:
- Cisco Nexus 3000 Series Switches
- Cisco Nexus 9000 Series Switches
- Cisco NX-OS
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Install the updates provided by the vendor; details in the sources below.
Is the vulnerability already being exploited?
None of the CVEs is in the CISA catalogue of exploited vulnerabilities. That does not mean there are no attacks, only that none are documented.
Information and sources
- Original BSI advisory (WID)
- Cisco Security Advisory cisco-sa-bgp-iefab-3hb2pwtx vom 2026-05-20 sec.cloudapps.cisco.com
CVE: CVE-2026-20171
Source: BSI warning and information service (CERT-Bund); CISA. The assessment of the conditions is my reading of the BSI text; the external pages are in their original language.