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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.

CVE-2026-20212: Cisco Nexus 9000 RCE Flaw

Cisco disclosed CVE-2026-20212, a critical unauthenticated remote code execution flaw in the Silicon One integration of Nexus 9000 switches.

Cisco has disclosed CVE-2026-20212, a critical vulnerability in the Silicon One integration used by certain Nexus 9000 switches. The flaw allows an unauthenticated remote attacker to achieve remote code execution. The source excerpt does not state active exploitation or provide patch details.

SOCRadar · 12d agoVulnerabilityCVE-2026-20212

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 · 14d agoVulnerability

Cisco searched for IOS XR bugs and found so many it rolled them into an update release

Cisco patched three critical flaws, including CVE-2026-20212 unauthenticated remote root code execution in Nexus 9000 switches; no exploitation observed yet.

Cisco disclosed three critical-rated flaws found during a comprehensive internal security review. CVE-2026-20274 and CVE-2026-20279, both CVSS 9.8, affect the IOS XR carrier-grade operating system and are fixed in newly released versions. CVE-2026-20212 lets unauthenticated remote attackers execute code with root privileges on some Nexus 9000 Series Switches by reaching TCP ports 43210 and 43211 in the default Layer 3 VRF; no software fix exists yet, only infrastructure ACL mitigations. Cisco says it has not observed attacks against these flaws.

Cisco security advisory (AV26-876)

Canada's Cyber Centre relayed Cisco advisories covering a Nexus 9000 Silicon One RCE, IOS XR hardening, and denial-of-service flaws across IP phone lines.

The Canadian Centre for Cyber Security advisory AV26-876 lists Cisco vulnerabilities affecting IOS XR, Nexus 9000 Series switches, and several IP phone series. Included are a Nexus 9000 Silicon One remote code execution vulnerability, a September 2026 IOS XR security hardening release, and SIP software denial-of-service flaws in Desk Phone 9800, IP Phone 7800/8800, and Video Phone 8875. The Cyber Centre urges users and administrators to review the Cisco advisories and apply updates as they become available. No active exploitation is reported in the advisory.

Canadian Centre for Cyber Security · 13d agoAdvisory

Cisco Advance Notification for Publication of September 2, 2026, Security Advisories

Cisco PSIRT published September 2, 2026 advisories including critical IOS XR hardening fixes and a Nexus 9000 remote code execution flaw.

Cisco's PSIRT released its September 2, 2026 batch of security advisories, including a Cisco IOS XR Software security hardening release bundling six CVEs (CVE-2026-20274 through CVE-2026-20280) rated critical with CVSS 9.8. A separate critical (CVSS 9.8) remote code execution vulnerability, CVE-2026-20212, affects Nexus 9000 Series switches with Silicon One, and a high-severity (CVSS 7.5) denial-of-service flaw, CVE-2026-20281, affects the Desk Phone 9800 Series and related SIP phones. Administrators should review the advisories and prioritize patching the critical-rated issues.