CVE-2015-4038 in WP Membership Plugin
Summary
by MITRE
The WP Membership plugin 1.2.3 for WordPress allows remote authenticated users to gain administrator privileges via an iv_membership_update_user_settings action to wp-admin/admin-ajax.php.
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Analysis
by VulDB Data Team • 03/10/2025
The WP Membership plugin version 1.2.3 for WordPress contains a critical privilege escalation vulnerability that allows authenticated attackers to elevate their privileges to administrator level. This vulnerability exists within the plugin's handling of AJAX requests and specifically targets the iv_membership_update_user_settings action endpoint located at wp-admin/admin-ajax.php. The flaw represents a significant security weakness that undermines the fundamental access control mechanisms of WordPress installations using this plugin.
The technical implementation of this vulnerability stems from inadequate input validation and privilege checking within the plugin's administrative AJAX handler. When authenticated users submit requests to the admin-ajax.php endpoint with the specific iv_membership_update_user_settings action, the plugin fails to properly verify whether the requesting user possesses sufficient privileges to modify user settings. This oversight creates a path where users with lower privileges can manipulate the system to grant themselves administrator access, effectively bypassing the standard WordPress permission model that typically requires admin-level credentials for such operations.
From an operational standpoint, this vulnerability poses severe risks to WordPress installations that rely on the WP Membership plugin. An attacker who has gained access to any valid user account within the WordPress system can exploit this flaw to escalate their privileges without requiring additional credentials or complex attack vectors. The impact extends beyond simple privilege escalation as it allows full administrative control over the affected WordPress site, including the ability to modify content, install malicious plugins, alter user permissions, and potentially compromise the entire web application infrastructure. This vulnerability particularly affects sites where user registration is enabled and where the plugin is actively used for membership management.
The vulnerability aligns with CWE-284, which addresses improper access control, and represents a clear violation of the principle of least privilege in cybersecurity. It also maps to ATT&CK technique T1078 which covers valid accounts and privilege escalation tactics. Organizations using this plugin should immediately implement mitigations including updating to the patched version of the WP Membership plugin, implementing additional access controls, and monitoring for suspicious administrative activities. Security teams should also consider implementing network-level restrictions to limit access to the admin-ajax.php endpoint and ensure that proper authentication and authorization mechanisms are in place throughout the WordPress ecosystem.
The broader implications of this vulnerability highlight the importance of proper input validation and privilege checking in web applications, particularly within plugin ecosystems where third-party code can introduce unexpected security risks. This flaw demonstrates how seemingly minor implementation oversights in authentication systems can result in complete system compromise, emphasizing the need for comprehensive security testing and code reviews of all components within WordPress installations. Organizations should maintain updated inventories of all installed plugins and regularly audit their security posture to prevent similar vulnerabilities from being exploited in their environments.