CVE-2021-24150: 
WordPress vulnerability analysis and mitigation

The LikeBtn WordPress Like Button Rating plugin before version 2.6.32 contained an Unauthenticated Full-Read Server-Side Request Forgery (SSRF) vulnerability, identified as CVE-2021-24150. The vulnerability was discovered and publicly disclosed on February 6, 2021, affecting WordPress installations using the vulnerable plugin version (WPScan).

The vulnerability exists in the likebtn_like_button.php file where a hook allows unauthenticated ajax calls to the likebtn_prx() function. The function implements a flawed host-check mechanism that accepts any URL containing 'likebtn.com' in the host, even if it's part of a subdomain controlled by an attacker. The URL parameter must be specified in the GET parameter 'likebtn_q' as a Base64 encoded value. The vulnerability has been assigned a CVSS score of 7.5 (High) and is classified under CWE-918 (WPScan).

This vulnerability allows attackers to make the server issue requests to arbitrary URLs by exploiting the flawed host validation. Through this SSRF vulnerability, attackers can potentially access sensitive information stored on the local server or internal network resources (WPScan).

The vulnerability can be exploited by creating a malicious subdomain containing 'likebtn.com' (e.g., likebtn.com.attackerwebsite.bla), setting up a redirect to the target internal resource, and making a request to the WordPress site's admin-ajax.php with the encoded malicious URL. No authentication is required to exploit this vulnerability (WPScan).

The vulnerability has been fixed in version 2.6.32 of the LikeBtn WordPress plugin. Users are advised to update to this version or later to protect against potential SSRF attacks (WPScan).