Security Advisory 0216

Date: November 10, 2026

Revision	Date	Changes
1.0	November 10, 2026	Initial release

The CVE-ID tracking this issue: CVE-2026-120976
CVSSv3.1 Base Score: 6.0 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N)
CVSSv4.0 Base Score: 7.0 (CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N)
Common Weakness Enumeration: CWE-532: Insertion of Sensitive Information into Log File
This vulnerability is being tracked by BUG 1899357

Description

On affected platforms running Arista EOS with IEEE 802.1X authentication and MACsec using dynamically derived keys, sensitive authentication information may be recorded in diagnostic data during a Smart Switch Upgrade (SSU).

An attacker with administrative access on the device who obtains the affected diagnostic data could recover sensitive authentication information. This could potentially compromise the confidentiality and integrity of traffic protected by MACsec on the affected link.

The vulnerability is only exposed during and after an SSU reload where an active 802.1X session used for MACsec is present.

This issue was discovered internally by Arista, and the company is not aware of any malicious exploitation of this vulnerability in customer networks.

Vulnerability Assessment

Platform and Software Applicability Note

To determine actual exposure, operators should first check their software versions against the "Affected Software" list below. If your software release is not listed, your deployment is not vulnerable, regardless of the hardware platform in use.

Affected Software

EOS Versions

Release 4.36.2F and below in the 4.36.x train
Release 4.35.6M and below in the 4.35.x train
Release 4.34.8M and below in the 4.34.x train
Release 4.33.9M and below in the 4.33.x train
All releases in the 4.32.x train
End of Life software trains between 4.22.0F and 4.31 are also affected.

Affected Platforms

The following products are affected by this vulnerability:

Arista EOS-based products:

7388-8D Series
7500R/R2 Series
7800/R3/R3A Series
722XPM and 720XPM Series
750X Series
7050X3/X4 Series
7170 Series
7289R3 Series
7500R3 Series
7800R4 Series

The following product versions and platforms are not affected by this vulnerability:

Arista EOS-based products:

710 Series
720D Series
720XP Series
7010TX Series
7020R/R4 Series
7130 Series running EOS
7060X/X2/X4/X5/X6/XE7 Series
7260X/X3 Series
7280R/R2/R3/R3A/R4 Series
7300X/X3 Series
7320X Series
7358X4 Series
7368X4 Series
7388X5 Series
7700R4 Series
AWE 5000 Series
AWE 7200R Series
ZTX-7200 Series
CloudEOS
CloudVision eXchange, virtual or physical appliance
cEOS-lab
vEOS-lab

Wi-Fi Access Points
CloudVision CUE cloud service delivery
CloudVision Portal, virtual appliance or physical appliance(including the CV-CUE on premises software)
CloudVision Appliance Software
CloudVision as-a-Service
CloudVision AGNI - Cloud service delivery
CloudVision AGNI - Virtual or physical appliance
Arista Converged Cloud Fabric (formerly Big Switch BCF)
DANZ Monitoring Fabric (DMF) - Controller Appliance
DANZ Monitoring Fabric (DMF) - Analytics Node Appliance
DANZ Monitoring Fabric (DMF) - Recorder Node Appliance
DANZ Monitoring Fabric (DMF) - Service Node Appliance
Arista Multi Cloud Director (formerly Big Switch MCD)
Arista Network Detection and Response (NDR) Security Platform (Formerly Awake NDR)
Arista Edge Threat Management - Arista NG Firewall and Arista Micro Edge (Formerly Untangle)
Arista NetVisor OS, Arista NetVisor UNUM, and Insight Analytics (Formerly Pluribus)
VeloCloud Orchestrator (Formerly VeloCloud Orchestrator by Broadcom)
VeloCloud Gateway (Formerly VeloCloud Gateway by Broadcom)
VeloCloud Edge (Formerly VeloCloud Edge by Broadcom)

Required Configuration for Exploitation

In order to be vulnerable to CVE-2026-120976, the following condition must be met:

For the MACsec key exposure described in this advisory, a device must meet all of these following configuration conditions:

IEEE 802.1X authentication is configured on the affected interface.

A MACsec profile containing key source dot1x is applied to that same interface, enabling MACsec to derive keys from successful 802.1X authentication.

1.) 802.1X configuration

switch#show running-config section dot1x
dot1x system-auth-control
!
interface Ethernet1
   dot1x pae authenticator
   dot1x port-control auto

2.) MACsec configuration

switch#show running-config section mac security
mac security
   profile macsecDot1xProfile
      key source dot1x
!
interface Ethernet1
   mac security profile macsecDot1xProfile

Indicators of Compromise

There are no known indicators of compromise for this vulnerability.

Mitigation

There is no mitigation possible for this vulnerability.

Resolution

The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Arista recommends customers move to the latest version of each release that contains all the fixes listed below. For more information about upgrading see EOS User Manual: Upgrades and Downgrades

CVE-2026-120976 has been fixed in the following releases:

4.37.0F and later releases in the 4.37.x train
4.36.3M and later releases in the 4.36.x train
4.35.7M and later releases in the 4.35.x train
4.34.9M and later releases in the 4.34.x train
4.33.10M and later releases in the 4.33.x train

Hotfix

There is no hotfix available.

For More Information

If you require further assistance, or if you have any further questions regarding this security notice, please contact the Arista Networks Technical Assistance Center (TAC) by one of the following methods:

Open a Service Request
By email: This email address is being protected from spambots. You need JavaScript enabled to view it.
By telephone: List of regional telephone numbers

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