Description
A vulnerability with the Ethernet VPN (EVPN) Layer 2 ingress packet processing of Cisco Nexus 3600 Platform Switches and Cisco Nexus 9500-R Series Switching Platforms 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. An attacker could exploit this vulnerability by sending a stream of crafted Ethernet frames through the targeted device. A successful exploit could allow the attacker to cause a Layer 2 Virtual eXtensible LAN (VxLAN) traffic loop, which, in turn, could result in a denial of service (DoS) condition. This Layer 2 loop could oversubscribe the bandwidth on network interfaces, which would result in all data plane traffic being dropped. To exploit this vulnerability, the attacker must be Layer 2-adjacent to the affected device.
Note: To stop active exploitation of this vulnerability, manual intervention is required to both stop the crafted traffic and flap all involved network interfaces. For additional assistance if a Layer 2 loop that is related to this vulnerability is suspected, contact the Cisco Technical Assistance Center (TAC) or the proper support provider.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Cisco | Cisco NX-OS Software | 9.2(3), 9.2(2v), 9.2(1), 9.2(2t), 9.2(3y), 9.3(2), 9.2(4), 9.3(1), 9.3(1z), 9.2(2), 9.3(3), 9.3(4), 9.3(5), 9.3(6), 9.3(5w), 9.3(7), 9.3(7k), 10.2(1), 9.3(7a), 9.3(8), 10.2(1q), 10.2(2), 9.3(9), 10.2(3), 10.2(3t), 9.3(10), 10.2(2a), 10.3(1), 10.2(4), 10.3(2), 9.3(11), 10.3(3), 10.2(5), 9.3(12), 10.… | — |
Advisories 1
- WID-SEC-2026-0523 Cisco Nexus: Mehrere Schwachstellen ermöglichen Denial of Service BSI CERT-Bund (WID) · Feb 25, 2026