An issue has recently been discovered in Arista EOS where the incorrect use of EOS's AAA API’s by the OpenConfig and TerminAttr agents could result in unrestricted access to the device for local users with nopassword configuration.
The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Artista recommends customers move to the latest version of each release that contains all the fixes listed below. CVE-2021-28500 has been fixed in the following releases: 4.26.2F and later releases in the 4.26.x train 4.25.5M and later releases in the 4.25.x train 4.25.4.1M and later releases in the 4.25.4.x train 4.24.7M and later releases in the 4.24.x train 4.23.9M and later releases in the 4.23.x train 4.22.12M and later releases in the 4.22.x train 4.21.15M and later releases in the 4.21.x train
For local users whose authentication is with nopassword, enforce a password or remove the user. Ensure that the following configuration does not exist where a local user is configured with nopassword. To mitigate CVE-2021-28500 with the continued use of the affected agents, a hotfix employing a proxy service can be deployed. The proxy is configured behind the gNMI/gNOI or RESTCONF server. The hotfix can be downloaded at https://www.arista.com/en/support/advisories-notices/sa-download/?sa=71-SecurityAdvisory0071Hotfix.i386.swix for 32 bit systems and https://www.arista.com/en/support/advisories-notices/sa-download/?sa=71-SecurityAdvisory0071Hotfix.x86_64.swix for 64 bit systems.
| Product | Vulnerable range | Fixed version | Advisory |
|---|---|---|---|
| Arista Networks Arista EOS | >=4.20<0 | 0 | advisory ↗ |
| Arista Networks Arista EOS | >=4.21.14M<=4.21.0 | 4.21.0 | advisory ↗ |
| Arista Networks Arista EOS | >=4.22.11M<=4.22.0 | 4.22.0 | advisory ↗ |
| Arista Networks Arista EOS | >=4.23.8M<=4.23.0 | 4.23.0 | advisory ↗ |
| Arista Networks Arista EOS | >=4.24.6M<=4.24.6.0 | 4.24.6.0 | advisory ↗ |
| Arista Networks Arista EOS | >=4.25.4.M<=4.25.0 | 4.25.0 | advisory ↗ |
| Arista Networks Arista EOS | >=4.26.1F<=4.26.0 | 4.26.0 | advisory ↗ |