On affected platforms running Arista EOS, an authenticated user with access to the gNMI (gRPC Network Management Interface) may receive incorrect authorization results, potentially allowing access beyond their currently assigned permissions.
This issue was discovered internally by Arista and the company is not aware of any malicious uses of this issue in customer networks.
In order to be vulnerable to CVE-2026-19640, OpenConfig with authorized requests must be configured:
switch#show man api gnmi
Transport: default
Enabled: yes
Server: running on port 6030, in default VRF
SSL profile: oc
QoS DSCP: none
Connection limit: 100
Authorization required: yes
Accounting requests: no
Notification timestamp: last change time
Listen addresses: ::
Authentication username priority: x509-spiffe, metadata, x509-common-name
Config-commands AAA accounting: enabled
Config-commands AAA authorization: enabled
The vulnerability can be mitigated by performing both of the following actions.
- Kill gNMI subscriptions after AAA authorization policy changes. Run the following command to kill gNMI subscriptions to OpenConfig/Octa on port 6030. If a different port than the default of 6030 is being used for OpenConfig/Octa, adjust accordingly to that port:
switch#bash ss -tnp dport = 6030 | grep -o 'pid=[0-9]*' | cut -d= -f2 | xargs sudo kill
Note: the port that OpenConfig/Octa is running the gNMI transport on is available in the output of the "show man api gnmi" CLI command (see above under the "Server:" field).
- Use username and password based authentication (as opposed to mTLS) for gNMI requests to OpenConfig/Octa. The following command is an example using Arista's gNMI client:
gnmi -username bob -password myPass123 -addr 127.0.0.1 subscribe /system/state
For a transport running mTLS, mTLS can be disabled for this transport by any of the configurations described below:
a. Configure the SSL profile to use TLS instead of mTLS. This can be done by removing the trusted certificates from the SSL profile, using the "no trust certificate <name>" CLI command within the SSL profile.
For example, if an SSL profile has configuration like:
management security
ssl profile XXY
certificate x.crt key x.key
trust certificate A.crt
trust certificate B.crt
Then this profile can be changed from mTLS to TLS by removing each of the trusted certificates:
switch#configure
switch(config)#management security
switch(config-mgmt-security)#ssl profile XXY
switch(config-mgmt-sec-ssl-profile-XXY)#no trust certificate A.crt
switch(config-mgmt-sec-ssl-profile-XXY)#no trust certificate B.crt
b. Configure the OpenConfig/Octa transport to use an insecure server instead of mTLS, by removing the SSL profile config from the "transport grpc <name>" mode:
switch#configure
switch(config)#management api gnmi
switch(config-mgmt-api-gnmi)#transport grpc default
switch(config-gnmi-transport-default)#no ssl profile
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.
CVE-2026-19640 has been fixed in the following releases:
- 4.36.1F 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
- 4.33.9M and later releases in the 4.33.x train
No hotfix is available for this issue.