CVE-2026-20212

Critical

Description

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.

SeverityCritical
CVSS9.8
Exploit probability—
ProductCisco NX-OS Software
PublishedSep 2, 2026
First seenSep 2, 2026
Weakness typeCWE-1327CWE-1327

How to fix

Sources list no fixed version or patch link for this vulnerability.

Affected products

ProductAffected versionsFixed in
Cisco Cisco NX-OS Software10.3(1), 10.3(2), 10.3(3), 10.4(1), 10.3(99w), 10.3(3w), 10.3(99x), 10.3(3o), 10.3(4), 10.3(3p), 10.3(4a), 10.4(2), 10.3(3q), 10.3(5), 10.4(3), 10.3(3x), 10.3(4g), 10.5(1), 10.3(3r), 10.3(6), 10.4(4), 10.3(4h), 10.5(2), 10.3(7), 10.4(5), 10.5(3), 10.4(4g), 10.5(4), 10.6(1), 10.5(3t), 10.3(8), 10.4(6), 10.5(3s), 10.5(3e), 10.5(3o), 10.6(1s), 10.6(2), 10.5(3p), 10.3(9), 10.6(2s), 10.6(3), 10.4(7), 10.5(5), 10.6(2n), 10.6(3s)—

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