Brief Look: CVE-2025-12158 Privilege Escalation in Simple User Capabilities WordPress Plugin

Introduction

Attackers can gain full administrative control of WordPress sites running the Simple User Capabilities plugin up to version 1.0, simply by exploiting a missing capability check. This vulnerability enables privilege escalation for any user account, including unauthenticated attackers in some configurations, leading to total site compromise.

About Simple User Capabilities: Simple User Capabilities is a WordPress plugin that allows site administrators to manage user capabilities with fine granularity. It is distributed via the official WordPress plugin repository and is used by WordPress administrators who require more control over user permissions than the default role system provides. As of this vulnerability disclosure, only version 1.0 is available and there is no evidence of a mature security process or prior vulnerability history for this vendor.

Technical Information

The vulnerability exists in the suc_submit_capabilities() function of the Simple User Capabilities plugin. This function is exposed via a WordPress AJAX endpoint and is intended to allow administrators to modify user capabilities. However, it fails to perform a capability check before processing requests.

Mechanism:

• The function can be triggered by sending a POST request to wp-admin/admin-ajax.php with the action parameter set to the vulnerable function name (e.g., suc_submit_capabilities).
• The request can specify the target user and the desired capabilities.
• The plugin does not verify if the requester has sufficient privileges (such as manage_options or promote_users) before applying the changes.
• If the AJAX endpoint is registered with wp_ajax_nopriv_ or lacks authentication checks, unauthenticated users can exploit this flaw.

Root Cause:

• The absence of a call to WordPress's current_user_can() or similar authorization check in the vulnerable function.
• This is a classic case of CWE-862 (Missing Authorization), where access control is not enforced on sensitive operations.

Impact:

• Any user, including unauthenticated attackers (depending on endpoint registration), can escalate their own or any other account's privileges to administrator.
• Attackers can automate exploitation by crafting POST requests to the AJAX handler.

No public code snippet is available for this function, but the vulnerability is confirmed in public advisories and plugin source references.

Affected Systems and Versions

• Product: Simple User Capabilities WordPress plugin
• Affected Versions: All versions up to and including 1.0
• Vulnerable Configuration: Any WordPress site with the plugin installed and active. Exploitation may be possible by unauthenticated users if the endpoint is exposed via wp_ajax_nopriv_ or lacks authentication checks.

Vendor Security History

• No public record of previous vulnerabilities for Simple User Capabilities.
• No evidence of a mature security response process or history of timely patching.
• Only version 1.0 was available at the time of this vulnerability disclosure.

References

• NVD Entry for CVE-2025-12158
• Official CVE Entry
• WordPress Plugin Directory: Simple User Capabilities
• Plugin Source: user_access.php
• Wordfence Advisory