Like Button Rating ♥ LikeBtn <= 2.6.64 - Unauthenticated Stored Cross-Site Scripting via 'Client-IP' Header

The Like Button Rating ♥ LikeBtn plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'HTTP_CLIENT_IP (Client-IP header)' parameter in all versions up to, and including, 2.6.64 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Successful exploitation requires the site administrator to have disabled the default 'Be GDPR compliant' option, which would otherwise hash stored IP values and neutralize the payload. Successful exploitation additionally requires an action by an administrator — the attacker cannot trigger the vulnerability on their own.