CVE-2025-30767

Executive Summary

CVE-2025-30767 is a Missing Authorization vulnerability in the PDF for WPForms WordPress plugin (by 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 features or data exposure. The vulnerability affects all versions up to and including 5.3.0. 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 likelihood currently, but the risk remains due to the lack of a patch.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem. The plugin is distributed via the WordPress plugin repository and third-party sites. Users should verify the integrity of their plugin files and monitor for updates from the vendor.

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: 5.4 (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 stems from a Missing Authorization check (CWE-862) in the PDF generation functionality of the PDF for WPForms plugin. The plugin likely exposes AJAX actions or REST endpoints that generate PDFs from form submissions without verifying that the requesting user has the necessary permissions (e.g., admin or editor roles). An unauthenticated attacker can craft a request to trigger PDF generation for any form entry, potentially exposing sensitive data submitted through WPForms.

The core issue is that the plugin fails to call current_user_can() or similar authorization functions before executing privileged operations. This allows attackers to bypass access controls by directly calling the vulnerable endpoints.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the plugin's main PHP files (e.g., pdf-for-wpforms.php or an AJAX handler). A typical vulnerable pattern:

Vulnerable Code (hypothetical):

add_action('wp_ajax_nopriv_generate_pdf', 'generate_pdf_callback');
function generate_pdf_callback() {
    // No permission check
    $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();
}

Patched Code (hypothetical):

add_action('wp_ajax_generate_pdf', 'generate_pdf_callback'); // Only for authenticated users
add_action('wp_ajax_nopriv_generate_pdf', 'generate_pdf_callback_nopriv');
function generate_pdf_callback() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    // ... rest of the code
}
function generate_pdf_callback_nopriv() {
    wp_die('Unauthorized', 403);
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target WordPress site with PDF for WPForms plugin <= 5.3.0
• A valid form ID and entry ID (can be enumerated)

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=generate_pdf).
2. Craft a POST request with form_id and entry_id parameters.
3. Send the request without authentication.

Example cURL command:

curl -X POST http://target.com/wp-admin/admin-ajax.php \
  -d "action=generate_pdf&form_id=1&entry_id=5" \
  -o output.pdf

Note: No public exploit code is available; this is a hypothetical exploitation scenario.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with action parameters related to PDF generation (e.g., generate_pdf, pdf_for_wpforms).
• Look for requests from unauthenticated users (no Cookie header with WordPress auth cookies) to these endpoints.

Defense:

• Temporarily disable the plugin until a patch is released.
• Implement a Web Application Firewall (WAF) rule to block unauthenticated access to known vulnerable endpoints.
• Restrict access to admin-ajax.php using .htaccess or server-level rules for non-admin IPs.

Indicators of Compromise (IOCs)

• Network IOCs:

  • POST requests to /wp-admin/admin-ajax.php with action=generate_pdf (or similar) from unauthenticated sources.
  • Unusual PDF file downloads from the server without corresponding form submissions.

• File IOCs:

  • Unexpected PDF files in the server's upload or temp directories.
  • Modified plugin files (e.g., pdf-for-wpforms.php) if an attacker uploads a backdoor.

• Log IOCs:

  • Access logs showing admin-ajax.php requests with action parameters not preceded by a valid login session.
  • Error logs containing "Unauthorized" or "403" responses from the plugin.

Detection Engineering

YARA Rule

rule CVE_2025_30767_PDF_WPForms {
    meta:
        description = "Detects vulnerable PDF for WPForms plugin files"
        author = "Valters IT"
        date = "2025-04-17"
        reference = "CVE-2025-30767"
    strings:
        $vuln_func = "wp_ajax_nopriv_" nocase
        $pdf_action = "generate_pdf" nocase
        $missing_auth = "current_user_can" nocase
    condition:
        $vuln_func and $pdf_action and not $missing_auth
}

Sigma Rule

title: CVE-2025-30767 - Unauthenticated PDF Generation Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthenticated requests to PDF generation endpoints in PDF for WPForms plugin
author: Valters IT
date: 2025-04-17
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=generate_pdf'
        sc-status: 200
    filter:
        cs-cookie|contains: 'wordpress_logged_in'
    condition: selection and not filter
falsepositives:
    - Legitimate admin users generating PDFs
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-30767 - Unauthenticated PDF Generation Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"admin-ajax.php"; http_uri;
    content:"action=generate_pdf"; http_client_body;
    pcre:"/Cookie\s*:\s*(?!.*wordpress_logged_in)/Hi";
    sid:10000001;
    rev:1;
    reference:cve,2025-30767;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released by the vendor.
2. Implement a WAF rule to block unauthenticated POST requests to admin-ajax.php with action parameters containing "pdf".
3. Review server logs for any signs of exploitation.

Long-term Fix:

• Apply the official patch once released by add-ons.org.
• Update the plugin to the latest version.
• Conduct a security audit of all WordPress plugins for similar authorization flaws.

Workaround:

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

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

Valters IT
Securing Digital Frontiers