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High [CVE-2026-20033] Cisco Nexus 9000 Series Fabric Switches in ACI Mode Denial of Service Vulnerability

This high-severity Cisco advisory covers CVE-2026-20033 affecting Cisco NX-OS System Software in ACI Mode 15.2(1g), Cisco NX-OS System Software in ACI Mode 15.2(2e), Cisco NX-OS System Software in ACI Mode 15.2(2f).

cisco-sa-nxos-cpdos-qLsv6pFD Published Feb 25, 2026Updated by vendor Feb 25, 2026

CVE-2026-20033

Affected products & platforms

CiscoSwitchesNexusNX-OSNexus 9000

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Summary

A vulnerability in Cisco Nexus 9000 Series Fabric Switches in ACI mode could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient validation when processing specific Ethernet frames.

An attacker could exploit this vulnerability by sending a crafted Ethernet frame to the management interface of an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.

Note: Only the out-of-band (OOB) management interface is affe…

Affected products named by the advisory: Cisco NX-OS System Software in ACI Mode 15.2(1g); Cisco NX-OS System Software in ACI Mode 15.2(2e); Cisco NX-OS System Software in ACI Mode 15.2(2f); Cisco NX-OS System Software in ACI Mode 15.2(2g); and 4 more.

Affected versions

Scope: This vulnerability affects Cisco Nexus 9000 Series Fabric Switches in ACI mode if they have a configured and active OOB management interface.

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Fixed versions

No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Mitigation checklist

Workaround status

There are no workarounds that address this vulnerability.

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Sources

Official and corroborating records used to build this advisory.

Cisco Security Advisories (PSIRT)official
Official vendor feed — the source of truth for this advisory. VulniPulse polled this feed and parsed this entry from it. Discovered from the machine-readable feed https://sec.cloudapps.cisco.com/security/center/psirtrss20/CiscoSecurityAdvisory.xml; this link opens the Cisco advisory index instead of the raw feed document.
Cisco
Vendor advisory pageofficial
Advisory page fetched and parsed to extract affected/fixed versions and mitigation guidance beyond what the feed carries.
Cisco

Cross-references

Validate CVE metadata against the authoritative registries.

CVE-2026-20033NVD CVE.org MITRE

Official resources

Cisco Nexus (NX-OS) upgrade guide
Official documentation
Official upgrade documentation for Cisco Nexus switches running NX-OS.
Cisco Software Checker
Official documentation
Official tool to confirm whether your exact IOS / IOS XE / NX-OS / ASA / FTD / SD-WAN release is affected and to find the first fixed release.

Discussion(0)

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