Network ACL entries that allow all TCP or UDP ports significantly broaden the attack surface and can expose many services to network-based attacks and lateral movement.
For AWS::EC2::NetworkAclEntry resources where Protocol indicates TCP (6) or UDP (17), the PortRange property must be present, include both From and To, and must not be set to the full range From: 0 and To: 65535. Resources missing PortRange, missing the From/To attributes, or configured to allow 0–65535 will be flagged.
To remediate, restrict PortRange to specific ports or narrow ranges required by the application.
Secure example with a single allowed port (HTTPS):