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Cisco Fixed Critical RCE in Nexus 9000 Series Switches

Cisco patched CVE-2026-20212 (CVSS 9.8) in Silicon One-based Nexus 9000 switches, allowing unauthenticated remote root code execution via TCP ports 43210/43211.

Cisco patched CVE-2026-20212 (CVSS 9.8), a flaw in the Silicon One integration for Nexus 9000 Series switches that lets unauthenticated remote attackers execute code with root privileges. TCP ports 43210 and 43211 are exposed through the default Layer 3 VRF, and exploitation can also crash the S1HAL process, forcing device reloads. Cisco TAC discovered the flaw during a support case; PSIRT is not aware of public disclosure or malicious exploitation. Workarounds include infrastructure ACLs or blocking the exposed ports, alongside a Live Protect shield pending fixed NX-OS upgrades.

Security Affairs · 12d agoVulnerabilityCVE-2026-20212

Critical Cisco Nexus 9000 Flaw Lets Unauthenticated Remote Attackers Run Code as Root

Cisco patches critical CVE-2026-20212 (CVSS 9.8) in Nexus 9000 switches allowing unauthenticated remote root code execution, plus IOS XR hardening release.

Cisco released fixes for CVE-2026-20212 (CVSS 9.8), a flaw in 10 Silicon One-based Nexus 9000 switch models that binds a service to an unrestricted IP, leaving TCP ports 43210/43211 reachable in the default Layer 3 VRF and allowing unauthenticated remote attackers to execute code as root; exploitation attempts can also crash the S1HAL process. 45 NX-OS releases (10.3(1) through 10.6(3s)) are affected, with mitigations including infrastructure ACLs, the Live Protect shield lp00031, and fixed releases identified via Cisco's Software Checker. Cisco simultaneously issued an IOS XR hardening release bundling 7 umbrella CVEs, two rated 9.8 (CVE-2026-20274 for memory-safety bugs and CVE-2026-20279 for access-control bugs), affecting all releases with SMUs available for 14 releases and upgrades required for 93 of 111 listed releases. No malicious exploitation was reported as of the September 2 disclosure.

Cisco Nexus 9000 Series Switches Silicon One Remote Code Execution Vulnerability

Cisco patches unauthenticated RCE in Nexus 9000 Silicon One switches exposed via TCP ports 43210 and 43211 in the default L3 VRF.

Cisco disclosed and patched a vulnerability in the Silicon One integration for Nexus 9000 Series switches that allows an unauthenticated remote attacker to execute code with root privileges. The flaw stems from TCP ports 43210 and 43211 being accessible in the default Layer 3 VRF. Exploitation can also crash the S1HAL process and force an affected device to reload. Cisco has released software updates, and workarounds are available to mitigate exposure.

Cisco Security Advisories · 13d agoVulnerability