Overview
The Common Vulnerabilities and Exposures (CVE) system has recently identified a critical vulnerability, assigned as CVE-2025-5821, present in the Case Theme User plugin for WordPress. This vulnerability, which affects all versions of the plugin up to and including 1.0.3, is a severe Authentication Bypass flaw that could potentially result in system compromise or data leakage. The vulnerability is particularly concerning because it can be exploited by unauthenticated attackers who have an existing account on the WordPress site and access to the administrative user’s email. Given the popularity of WordPress and the widespread usage of its plugins, the discovery of this vulnerability necessitates immediate action.
Vulnerability Summary
CVE ID: CVE-2025-5821
Severity: Critical (CVSS:9.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System Compromise, Data Leakage
Affected Products
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Product | Affected Versions
Case Theme User Plugin for WordPress | Up to and including 1.0.3
How the Exploit Works
The vulnerability lies in the plugin’s faulty user authentication process, specifically within the facebook_ajax_login_callback() function. This function is meant to securely verify user login data, but it fails to properly log the user in with the previously validated data. This allows an unauthenticated attacker with an existing account on the site, and access to the administrative user’s email, to bypass the authentication process and log in as an administrative user.
Conceptual Example Code
While the specific exploit code can vary, the following is a conceptual example of how the vulnerability might be exploited:
POST /wp-admin/admin-ajax.php HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
action=facebook_ajax_login_callback&email=admin@example.com&password=attacker_passwordIn the above example, the attacker sends a POST request to the ‘admin-ajax.php’ endpoint, which is the AJAX API for WordPress and is also used by the vulnerable plugin. The action parameter in the request body is set to ‘facebook_ajax_login_callback’, invoking the vulnerable function. The attacker also includes the email of an administrative user and their own password in the request.
Mitigation
To mitigate this vulnerability, users of the Case Theme User plugin for WordPress are recommended to apply the vendor-supplied patch immediately. If a patch cannot be applied right away, users should implement a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) as a temporary measure to prevent exploitation. It is also advised to regularly update all WordPress plugins and to follow best security practices, such as using strong, unique passwords and enabling multi-factor authentication.