CVE-2025-54040

Executive Summary

CVE-2025-54040 is a Missing Authorization vulnerability in the Webba Booking WordPress plugin (webba-booking-lite). This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or modification. The vulnerability affects all versions up to and including 5.1.20. As of this report, no official patch has been released, and no public proof-of-concept (PoC) code is available. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant due to the lack of authentication requirements.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem. The plugin is distributed via the official WordPress plugin repository and third-party marketplaces. Users are advised to monitor for updates from the vendor (Webba) and consider disabling the plugin until a patch is available.

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: 6.5 (Medium)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. The vulnerability is exploitable remotely without authentication, but the impact is limited to low confidentiality and integrity loss. However, in the context of a WordPress site, this could lead to booking data exposure or manipulation.

Deep Dive & Mechanics

The vulnerability stems from missing authorization checks in the Webba Booking plugin's REST API endpoints or AJAX handlers. Specifically, the plugin fails to verify user capabilities before processing requests to access or modify booking data. This allows any unauthenticated user to:

• View sensitive booking information (e.g., customer names, appointment details).
• Modify or cancel bookings without proper permissions.
• Potentially escalate privileges if combined with other vulnerabilities.

The flaw is classified under CWE-862: Missing Authorization, meaning the software does not perform any authorization check when an actor attempts to access a resource or perform an action.

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical fix would involve adding capability checks to all sensitive endpoints. Below is an example of vulnerable vs. patched code for a typical WordPress AJAX handler.

Vulnerable Code (webba-booking-lite <= 5.1.20):

add_action('wp_ajax_nopriv_webba_get_bookings', 'webba_get_bookings');
function webba_get_bookings() {
    $bookings = get_option('webba_bookings');
    wp_send_json_success($bookings);
}

Patched Code (Hypothetical):

add_action('wp_ajax_nopriv_webba_get_bookings', 'webba_get_bookings');
function webba_get_bookings() {
    if (!current_user_can('manage_options')) {
        wp_send_json_error('Unauthorized');
        return;
    }
    $bookings = get_option('webba_bookings');
    wp_send_json_success($bookings);
}

Exploitation & Lab Setup

Red Team (Exploitation)

Since no public PoC exists, exploitation would require crafting a direct HTTP request to the vulnerable endpoint. Example using curl:

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

If the endpoint returns booking data without authentication, the vulnerability is confirmed. Attackers could also attempt to modify bookings by sending POST requests with modified parameters.

Blue Team (Detection & Hardening)

• Immediate Action: Disable the Webba Booking plugin until a patch is available.
• Web Application Firewall (WAF): Block requests to admin-ajax.php with suspicious action parameters related to Webba.
• Log Monitoring: Monitor for unusual access to AJAX endpoints without authentication.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /wp-admin/admin-ajax.php with action=webba_* parameters from unauthenticated sources.
  • Unusual POST requests to booking-related endpoints.
• File IOCs:
  • Presence of the plugin directory: /wp-content/plugins/webba-booking-lite/
• Log IOCs:
  • Repeated 200 responses to admin-ajax.php without prior login.

Detection Engineering

YARA Rule

rule CVE_2025_54040_Webba_Booking_Missing_Auth {
    meta:
        description = "Detects Webba Booking plugin files vulnerable to CVE-2025-54040"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-54040"
    strings:
        $vuln_func = "wp_ajax_nopriv_webba" nocase
        $auth_check = "current_user_can" nocase
    condition:
        $vuln_func and not $auth_check
}

Sigma Rule

title: CVE-2025-54040 - Webba Booking Missing Authorization
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects unauthenticated access to Webba Booking AJAX endpoints
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=webba_'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate admin actions (if authenticated)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-54040 - Webba Booking Missing Authorization"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=webba_"; http_client_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable the Webba Booking plugin if not critical.
2. Short-term: Implement a virtual patch using a WAF to block unauthenticated requests to admin-ajax.php with action=webba_* parameters.
3. Long-term: Monitor the vendor's website for a patched version (>= 5.1.21). Apply the update as soon as it becomes available.
4. Alternative: Consider switching to a different booking plugin with active security support.

Valters IT
Securing Digital Frontiers