Discourse is a platform for community discussion. A malicious admin could use this vulnerability to perform port enumeration on the local host or other hosts on the internal network, as well as against hosts on the Internet. Latest "stable", "beta", and "test-passed" versions are now patched. As a workaround, self-hosters can use "DISCOURSE_BLOCKED_IP_BLOCKS" env var (which overrides "blocked_ip_blocks" setting) to stop webhooks from accessing private IPs.