CVE-2021-28500

Public Exploit
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.

Description

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.

Remediation

Solution:

  • 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

Workaround:

  • 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.

Category

9.1
CVSS
Severity: Critical
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.31%
Vendor Advisory arista.com
Affected: Arista Networks Arista EOS
Published at:
Updated at:

References

Link Tags
https://www.arista.com/en/support/advisories-notices/security-advisories/13449-security-advisory-0071 patch exploit vendor advisory mitigation

Frequently Asked Questions

What is the severity of CVE-2021-28500?
CVE-2021-28500 has been scored as a critical severity vulnerability.
How to fix CVE-2021-28500?
To fix CVE-2021-28500: 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
Is CVE-2021-28500 being actively exploited in the wild?
It is possible that CVE-2021-28500 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-28500?
CVE-2021-28500 affects Arista Networks Arista EOS.
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