Product:
Nexus 3600 Platform Switches and Nexus 9500-R Series Switching Platforms
Summary
A vulnerability with the Ethernet VPN Layer 2 ingress packet processing could allow an unauthenticated, adjacent attacker to trigger a Layer 2 traffic loop. This vulnerability is due to a logic error when processing a crafted Layer 2 ingress frame. A successful exploit could result in a denial of service condition by oversubscribing the bandwidth on network interfaces.
Details
| Severity | Base Score | CVE |
|---|---|---|
| HIGH | 7.4 | CVE-2026-20051 |
Exploitation
To exploit this vulnerability, an attacker must be Layer 2-adjacent to the affected device and send a stream of crafted Ethernet frames through it. This crafted traffic can create a Layer 2 Virtual eXtensible LAN traffic loop, leading to all data plane traffic being dropped. Manual intervention is required to stop the crafted traffic and reset the involved network interfaces.
Affected Products
- Nexus 3600 Platform Switches: Vulnerable to Layer 2 traffic loop due to logic error in packet processing.
- Nexus 9500-R Series Switching Platforms: Susceptible to denial of service through crafted Ethernet frames.
Mitigation
To mitigate this vulnerability, it is essential to stop the crafted traffic and flap all involved network interfaces. For further assistance, contacting the Cisco Technical Assistance Center or the appropriate support provider is recommended.