CVE-2025-68534

Executive Summary

CVE-2025-68534 is a Missing Authorization vulnerability in the PDF for WPForms WordPress plugin (vendor: add-ons.org). This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized access to PDF generation functionality or data exposure. The vulnerability affects all versions up to and including 6.3.0. As of this report, no official patch has been released, and no public proof-of-concept (PoC) or exploit code is available. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant for sites using this plugin.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem. WordPress plugins are often distributed via the official WordPress Plugin Directory or third-party marketplaces. Users should verify the integrity of their plugin files and ensure they are sourced from trusted repositories. No known supply chain compromise has been reported for this specific plugin.

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 (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – The exploit does not affect other components.
• Confidentiality Impact: Low (C:L) – Limited data exposure possible.
• Integrity Impact: Low (I:L) – Limited modification possible.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. While the CVSS score is 6.5, the lack of public exploits and low EPSS score reduce immediate risk. However, the absence of a patch makes it a persistent threat for unpatched installations.

Deep Dive & Mechanics

The vulnerability stems from a Missing Authorization check (CWE-862) in the PDF generation functionality of the plugin. The plugin likely exposes AJAX actions or REST endpoints that generate PDFs from WPForms submissions. Without proper capability checks, an unauthenticated attacker can invoke these endpoints to:

• Generate PDFs of any form submission (if IDs are enumerable).
• Access sensitive data contained in form entries (e.g., PII, financial data).
• Potentially trigger resource exhaustion by generating many PDFs.

The flaw is in the pdf-for-wpforms plugin, specifically in the code that handles PDF generation requests. The plugin fails to verify that the requesting user has the necessary permissions (e.g., manage_options or edit_posts) before processing the request.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable pattern. A typical vulnerable code snippet might look like:

// Vulnerable: No permission check
add_action('wp_ajax_nopriv_generate_pdf', 'generate_pdf_callback');
add_action('wp_ajax_generate_pdf', 'generate_pdf_callback');

function generate_pdf_callback() {
    $form_id = $_POST['form_id'];
    $entry_id = $_POST['entry_id'];
    // Generate PDF without checking user capabilities
    $pdf = new PDF_Generator($form_id, $entry_id);
    $pdf->output();
}

A patched version would include a capability check:

// Patched: Check user capabilities
add_action('wp_ajax_generate_pdf', 'generate_pdf_callback');

function generate_pdf_callback() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $form_id = $_POST['form_id'];
    $entry_id = $_POST['entry_id'];
    $pdf = new PDF_Generator($form_id, $entry_id);
    $pdf->output();
}

Note: The nopriv hook (for unauthenticated users) should be removed entirely for privileged actions.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with PDF for WPForms plugin version <= 6.3.0.
• Knowledge of a valid form ID and entry ID (can be brute-forced if IDs are sequential).

Exploitation Steps:

1. Identify the vulnerable endpoint: Use browser developer tools or intercept traffic to find AJAX actions related to PDF generation (e.g., admin-ajax.php?action=generate_pdf).

2. Craft a request: Send a POST request to the vulnerable endpoint with form and entry IDs.

curl -X POST http://target.com/wp-admin/admin-ajax.php \
  -d "action=generate_pdf&form_id=1&entry_id=1"

3. Extract data: The response will contain the generated PDF, which may include sensitive form data.

Note: No public exploit code is available. The above is a conceptual example.

Blue Team (Defense)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with actions related to PDF generation from unauthenticated users.
• Look for sequential or brute-forced entry IDs in logs.

Mitigation:

• Disable the plugin until a patch is available.
• Implement a Web Application Firewall (WAF) rule to block requests to the vulnerable endpoint from unauthenticated users.
• Restrict access to wp-admin/admin-ajax.php using IP whitelisting or .htaccess rules.

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /wp-admin/admin-ajax.php with action=generate_pdf (or similar) from unauthenticated sources.
  • Repeated requests with sequential form_id or entry_id parameters.
• File System:
  • Unexpected PDF files in the server's temporary directory or uploads folder.
• Logs:
  • HTTP 200 responses to admin-ajax.php without a valid wpnonce or authentication cookie.

Detection Engineering

YARA Rule

rule CVE_2025_68534_PDF_WPForms {
    meta:
        description = "Detects exploitation attempts for CVE-2025-68534 in PDF for WPForms"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-68534"
    strings:
        $ajax_action = "action=generate_pdf" nocase
        $form_id = "form_id=" nocase
        $entry_id = "entry_id=" nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2025-68534 - Missing Authorization in PDF for WPForms
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects unauthenticated requests to the PDF generation endpoint
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=generate_pdf'
        c-ip|notcontains: '127.0.0.1'
    condition: selection
falsepositives:
    - Legitimate admin requests (should include authentication)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-68534 - PDF for WPForms Missing Authorization"; flow:to_server,established; content:"POST"; http_method; content:"admin-ajax.php"; http_uri; content:"action=generate_pdf"; http_client_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until an official patch is released.
2. Apply a virtual patch using a WAF to block unauthenticated requests to the PDF generation endpoint.
3. Review server logs for any signs of exploitation.

Long-term Fix:

• Monitor the vendor's website (add-ons.org) for a patched version.
• Once available, update to the latest version immediately.
• Implement the principle of least privilege for all WordPress plugins.

Workaround:

• Add the following code to your theme's functions.php to block unauthenticated access:

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

Valters IT
Securing Digital Frontiers