A critical remote code execution vulnerability (CVE-2026-20212, CVSS 9.8) in the Silicon One integration for Cisco Nexus 9000 Series Switches allows an unauthenticated attacker to execute arbitrary code with root privileges by sending crafted input to accessible TCP ports 43210 and 43211 in the default L3 VRF. Cisco has released software updates to address this vulnerability and has provided workarounds.
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. Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-n9k-s1-rce-EH8dEtr <br/>Security Impact Rating: Critical <br/>CVE: CVE-2026-20212