Ethernet VPN Vulnerability in Cisco Nexus 3600 and 9500-R Series Platforms

CVE-2026-20051

What is CVE-2026-20051?

A vulnerability exists in the Ethernet VPN (EVPN) Layer 2 ingress packet processing of the Cisco Nexus 3600 Platform Switches and Cisco Nexus 9500-R Series Switching Platforms. This issue arises from a logic error that could be exploited by an unauthenticated adjacent attacker through a stream of crafted Ethernet frames. The exploitation of this vulnerability may result in a Layer 2 traffic loop, leading to a denial of service by oversubscribing network interface bandwidth and causing all data plane traffic to be dropped. Immediate manual intervention is necessary to halt the crafted traffic and reset all involved network interfaces. For any suspected incidents, it is recommended to contact Cisco Technical Assistance Center (TAC) or the relevant support provider.

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