A security issue exists within CompactLogix® 5380, ControlLogix® 5580, and EN4 communication modules related to CIP Security certificate revocation handling. The security issue stems from the controller failing to properly reject certificates signed by an intermediate certificate that has been revoked via a Certificate Revocation List (CRL). This could allow a network-based attacker to establish a connection using a certificate that should be untrusted, potentially bypassing CIP Security protections.