Security Advisory 0178 PDF

Date: September 9, 2026

Revision Date Changes
1.0 September 9, 2026 Initial release

The CVE-ID tracking this issue: CVE-2026-73440
CVSSv3.1 Base Score: 4.2 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N)
CVSSv4.0 Base Score: 2.3 (CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N) Common Weakness Enumeration: CWE-212: Improper Removal of Sensitive Information Before Storage or Transfer
This vulnerability is being tracked by BUG1856462(EOS) and BUG 1966273 (DMF)

Description

On affected platforms running Arista EOS with Simple Network Management Protocol (SNMP) configured, SNMPv3 local or remote user credentials may be exposed as a one-way hashed, localized key value within the device’s running and sanitized configurations. An authenticated user who gains access to this sensitive information could leverage it to perform unauthorized read operations on SNMP tables or to send fraudulent trap notifications to the Network Management System (NMS).

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
 
  • 4.36.1F and below releases in the 4.36.x train
  • 4.35.5M and below releases in the 4.35.x train
  • 4.34.7.1M and below releases in the 4.34.x train
  • 4.33.9M and below releases in the 4.33.x train
  • All prior releases

Impact on DANZ Monitoring Fabric (DMF)

DANZ Monitoring Fabric (DMF) deploys a fixed version of Arista EOS on certain managed fabric switches. If the EOS version bundled with a DMF release falls within the affected version range of this advisory, DMF deployments using EOS-based switch platforms may be impacted.

DMF fabric switches running Switch Light OS are not affected by this vulnerability.

Customers running DMF should run the following command on the controller to identify the EOS version bundled with their deployment.

DMF-CONTROLLER> show version details
...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Platform files ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
File
Hcl supported Platform
--------------------------------------------------------------------------------|-------------|----------------------------|
...
EOS-4.36.2F-49446791.volgarel.1-x86_64.swi                                            True          x86_64-7289-eos
EOS-4.36.2F-49446791.volgarel.1-x86_64.swi                                            True          i686-7289-eos
EOS-4.36.2F-49446791.volgarel.1-x86_64.swi                                            False         x86_64-ccs-720df-48y-eos
 

The above switches are running EOS 4.36.2F as shown in the first column

Affected Platforms

The following products are affected by this vulnerability:
 
  • Arista EOS-based products:
    • 710 Series
    • 720D Series
    • 720XP/722XPM Series
    • 750X Series
    • 7010TX Series 
    • 7020R/R4 Series
    • 7130 Series running EOS
    • 7150 Series
    • 7170 Series
    • 7050X3/X4 Series
    • 7060X/X2/X4/X5/X6 Series
    • 7260X/X3 Series
    • 7280R/R2/R3/R4 Series
    • 7300X/X3 Series
    • 7320X Series
    • 7358X4 Series
    • 7368X4 Series
    • 7388X5 Series
    • 7500R/R2/R3 Series
    • 7800R3/R4 Series
    • 7700R4 Series
    • AWE 5000 Series
    • AWE 7200R Series
    • CloudEOS
    • cEOS-lab
    • vEOS-lab
    • CloudVision eXchange, virtual or physical appliance
 

 

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

 

  • Wi-Fi Access Points
  • CloudVision CUE, virtual appliance or physical appliance
  • CloudVision CUE cloud service delivery
  • CloudVision Portal, virtual appliance or physical appliance
  • CloudVision Appliance Software
  • CloudVision as-a-Service
  • CloudVision AGNI - Cloud service delivery
  • CloudVision AGNI - Virtual or physical appliance
  • Arista 7130 Systems running MOS
  • 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-2026-73440, the following conditions must all be met:
 
  • SNMPv3 must be configured with at least one local or remote user that has an authentication key
     
  • The SNMPv3 user CLI configuration uses the legacy syntax and does not include the updated key <algo> <encrypted_text> syntax as instructed in the Resolution section below.

SNMPv3 must be configured with at least one local or remote user that has an authentication key. For example:

switch# show running-config | section snmp-server
snmp-server user alice group_alice v3 localized f5717f2cdde9bb946d00 
auth sha256
f4b9ec9a299a10a5dec3541f44f44000484254ee56fa404236730520e10ce689
 

 

To verify whether any SNMPv3 users with authentication are configured:

 

switch# show snmp user
  
User name      : alice
Security model : v3
Engine ID      : f5717f2cdde9bb946d00
Authentication : SHA-256
Privacy        : None
Group          : group_alice
 

 

If SNMP is not configured or no SNMPv3 users are configured, there is no exposure to this issue and the show snmp output will look something like:

switch>show snmp
Chassis: XXXXXXXXXXX
SNMP agent enabled in VRFs: default
Transmit message maximum size: 65536
SNMP agent disabled: Either no communities and no users are configured, or no VRFs are configured.

Indicators of Compromise

No indicators of compromise exist.

Mitigation

No mitigation exists.

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.

 

Following the system upgrade, users are required to execute the syntax conversion command specified below to adopt the updated, encrypted SNMPv3 CLI format.

switch# configure convert new-syntax
 

  

The updated encrypted SNMPv3 CLI configuration follows this structure, incorporating the newly introduced key <algo> <encrypted_text> syntax:

switch# show running-config | grep snmp-server
snmp-server user alice group_alice v3 localized f5717f2cdde9bb946d00 
auth sha256 key 7
005D110205085E520B754E1B591C504542585F557D2F217064607A10034752035500080755575640440F5C00505053515F08525208035C1605525E0A040E781F4D
 

   

CVE-2026-73440 has been fixed in the following releases:
 

  

      • 4.36.2F and later releases in the 4.36.x train
      • 4.35.6M and later releases in the 4.35.x train
      • 4.34.8M and later releases in the 4.34.x train
      • 4.33.10M and later releases in the 4.33.x train

Hotfix

No hotfix is available for this issue.

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

Contact information needed to open a new service request may be found at:
https://www.arista.com/en/support/customer-support