GCP Firewall Rules are specific to a VPC Network. Each rule either allows or denies traffic when its conditions are met. Its conditions allow users to specify the type of traffic, such as ports and protocols, and the source or destination of the traffic, including IP addresses, subnets, and instances. More details can be found in https://cloud.google.com/vpc/docs/firewalls
Recommended Mitigation
Ensure vpc firewall rule in your account are configured to allow access to TCP port 5432 from specific IP addresses only.
Network misconfigurations
