A vulnerability in the Silicon One integration for Cisco Nexus 9000 Series Switches could allow an unauthenticated, remote attacker to execute code with root privileges. This vulnerability exists because TCP ports 43210 and 43211 are accessible in the default Layer 3 (L3) virtual routing and forwarding (VRF). A successful exploit could allow the attacker to connect to an affected device and send crafted input that could be executed as code with root privileges. The exploitation of this vulnerability could also cause the S1HAL process to crash, which could cause the device to reload.

A critical vulnerability in the Silicon One integration for Cisco Nexus 9000 Series Switches allows an unauthenticated remote attacker to execute arbitrary code with root privileges. The flaw exists due to TCP ports 43210 and 43211 being accessible by default in the Layer 3 virtual routing and forwarding (VRF) context. An attacker can connect to these open ports and send specially crafted input to trigger code execution at the root level. Additionally, successful exploitation can crash the S1HAL process, potentially causing the affected device to reload and resulting in a denial of service condition. No authentication is required to exploit this vulnerability, significantly lowering the barrier for attackers. The vulnerability is tracked as CVE-2026-20212 and is currently awaiting full analysis by NVD. Cisco has published a security advisory with further details and remediation guidance.