Accepting route advertisements belonging to the local AS can result in traffic looping or being black holed, or at a minimum using a non-optimized path. This requirement also applies to Zero Trust initiatives.
Review the router configuration to verify that it will reject routes belonging to the local AS. The prefix filter must be referenced inbound on the appropriate BGP neighbor statements. If the router is not configured to reject inbound route advertisements belonging to the local AS, this is a finding.
Ensure all eBGP routers are configured to reject inbound route advertisements for any prefixes belonging to the local AS.