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.
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.
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:
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.
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.
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
No hotfix is available for this issue.