CVE-2026-20212

Cisco Nexus 3000 and 9000 Series Switches Silicon One Hardware Abstraction Layer Remote Code Execution Vulnerability

Published Sep 2, 2026 CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed

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.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Cisco

Cisco NX-OS Software

unknown

Version	Status	Constraints
`10.3(1)`	affected	—
`10.3(2)`	affected	—
`10.3(3)`	affected	—
`10.4(1)`	affected	—
`10.3(99w)`	affected	—
`10.3(3w)`	affected	—
`10.3(99x)`	affected	—
`10.3(3o)`	affected	—
`10.3(4)`	affected	—
`10.3(3p)`	affected	—
`10.3(4a)`	affected	—
`10.4(2)`	affected	—
`10.3(3q)`	affected	—
`10.3(5)`	affected	—
`10.4(3)`	affected	—
`10.3(3x)`	affected	—
`10.3(4g)`	affected	—
`10.5(1)`	affected	—
`10.3(3r)`	affected	—
`10.3(6)`	affected	—
`10.4(4)`	affected	—
`10.3(4h)`	affected	—
`10.5(2)`	affected	—
`10.3(7)`	affected	—
`10.4(5)`	affected	—
`10.5(3)`	affected	—
`10.4(4g)`	affected	—
`10.5(4)`	affected	—
`10.6(1)`	affected	—
`10.5(3t)`	affected	—
`10.3(8)`	affected	—
`10.4(6)`	affected	—
`10.5(3s)`	affected	—
`10.5(3e)`	affected	—
`10.5(3o)`	affected	—
`10.6(1s)`	affected	—
`10.6(2)`	affected	—
`10.5(3p)`	affected	—
`10.3(9)`	affected	—
`10.6(2s)`	affected	—
`10.6(3)`	affected	—
`10.4(7)`	affected	—
`10.5(5)`	affected	—
`10.6(2n)`	affected	—
`10.6(3s)`	affected	—

No data.

Vendor Product Versions

Cisco

Nx-os Software

Version	Status	Scheme	Platform
`10.3(1)`	affected	generic	—
`10.3(2)`	affected	generic	—
`10.3(3)`	affected	generic	—
`10.4(1)`	affected	generic	—
`10.3(99w)`	affected	generic	—
`10.3(3w)`	affected	generic	—
`10.3(99x)`	affected	generic	—
`10.3(3o)`	affected	generic	—
`10.3(4)`	affected	generic	—
`10.3(3p)`	affected	generic	—
`10.3(4a)`	affected	generic	—
`10.4(2)`	affected	generic	—
`10.3(3q)`	affected	generic	—
`10.3(5)`	affected	generic	—
`10.4(3)`	affected	generic	—
`10.3(3x)`	affected	generic	—
`10.3(4g)`	affected	generic	—
`10.5(1)`	affected	generic	—
`10.3(3r)`	affected	generic	—
`10.3(6)`	affected	generic	—
`10.4(4)`	affected	generic	—
`10.3(4h)`	affected	generic	—
`10.5(2)`	affected	generic	—
`10.3(7)`	affected	generic	—
`10.4(5)`	affected	generic	—
`10.5(3)`	affected	generic	—
`10.4(4g)`	affected	generic	—
`10.5(4)`	affected	generic	—
`10.6(1)`	affected	generic	—
`10.5(3t)`	affected	generic	—
`10.3(8)`	affected	generic	—
`10.4(6)`	affected	generic	—
`10.5(3s)`	affected	generic	—
`10.5(3e)`	affected	generic	—
`10.5(3o)`	affected	generic	—
`10.6(1s)`	affected	generic	—
`10.6(2)`	affected	generic	—
`10.5(3p)`	affected	generic	—
`10.3(9)`	affected	generic	—
`10.6(2s)`	affected	generic	—
`10.6(3)`	affected	generic	—
`10.4(7)`	affected	generic	—
`10.5(5)`	affected	generic	—
`10.6(2n)`	affected	generic	—
`10.6(3s)`	affected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

No advisories available

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.831% probability within 30 days)

Exploitation none

Automatable yes

Technical Impact total

References

Link	Providers
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-n9k-s1-rce-EH8dEtr

History

Sep 3, 2026 3:45 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Cisco Cisco nx-os Software
Vendors & Products		Cisco Cisco nx-os Software

Sep 3, 2026 5:30 AM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}`

Sep 2, 2026 4:30 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
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.
Title		Cisco Nexus 3000 and 9000 Series Switches Silicon One Hardware Abstraction Layer Remote Code Execution Vulnerability
Weaknesses		CWE-1327
References		https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-n9k-s1-rce-EH8dEtr
Metrics		cvssV3_1 `{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}`