Currently, an explicit locally configured listen-address is required in the webproxy configuration. But there might be situations when an IP address assigning dynamically or can change during work. For such cases, the http_port option in the squid.conf should contain IP address 0.0.0.0 or only port value.
Of course, this is an insecure config, but it can be protected by a firewall rule.
We need to allow 0.0.0.0 in listen-address or make it non-mandatory to fix this.