On affected platforms running Arista EOS with Border Gateway Protocol (BGP) changing the BGP listen port from its default value disables default protective Access Control List (ACL) rules against unexpected BGP peering attempts.
Affected Arista EOS platforms are exposed when BGP is in use and the BGP listen port has been changed from its default value. The advisory data does not indicate that deployments retaining the default BGP listen port are affected.
An attacker would need network access sufficient to make an unexpected BGP peering attempt to the affected device. No privileges or user interaction are required according to the supplied severity vector.
Changing the port disables the default protective ACL rules that normally block unexpected BGP peering attempts. This can allow unauthorized peering attempts that those default rules would otherwise prevent.
Determine whether BGP is enabled and whether its listen port differs from the default value. Also verify whether equivalent ACL protections have been explicitly configured for the non-default port.