ProcessWire is a popular open-source PHP content management system (CMS) used by thousands of websites, prized for its flexibility and lightweight design. However, even the best tools can have vulnerabilities. In late 2022, security researchers identified a severe security flaw—designated CVE-2022-40487—that exposes users and their sites to the risk of Cross-Site Scripting (XSS) attacks. This flaw affects ProcessWire v3..200, specifically within the Search Users and Search Pages functions.

This deep dive explains what the issue is, how it can be exploited, and what you can do to stay safe. We provide easy-to-understand explanations, direct code snippets, and practical advice.

⭐ Quick Explainer: What is XSS?

Cross-Site Scripting (XSS) is a security vulnerability that lets an attacker inject malicious scripts into web pages viewed by other users. If a site is vulnerable to XSS, an attacker may be able to:

📋 The Vulnerability: Where Does It Occur?

In version 3..200 of ProcessWire, both the Search Pages and Search Users features do not properly sanitize user input before displaying it. This means that whatever you type into these search boxes may end up being rendered into the HTML output of the page, including scripts or other HTML code.

Let’s look at a typical search form in ProcessWire

<form id="SearchForm" action="/admin/search/" method="get">
    <input type="text" name="q" value="" placeholder="Search pages...">
    <input type="submit" value="Search">
</form>

After submitting the form, your search query gets echoed back on the results page. If the value isn’t properly escaped, attackers can inject HTML or JavaScript.

Suppose an attacker searches for

"><script>alert('XSS')</script>

If that input is reflected on the page like this

<input type="text" name="q" value=""><script>alert('XSS')</script>" placeholder="Search pages...">

🛠️ Proof of Concept: Exploiting the XSS

Here’s a step-by-step for exploiting the XSS vulnerability in ProcessWire 3..200, as found by researchers.

Step 1: Log in as a normal (non-admin) user

This attack works as any logged-in user with search capabilities.

Let’s use a common XSS payload

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

Step 3: Submit the Payload

Go to the Users or Pages search bar, and enter the above payload as your search string.

Step 4: Trigger the Vulnerability

After submission, if ProcessWire is unpatched, the page will render the payload, resulting in a popup alert (or whatever your script does).

Sample reflected output (unsafe)

<input type="text" name="q" value=""><img src=x onerror=alert('xss')>" placeholder="Search users...">

A simple code example from a vulnerable ProcessWire template could look like this

<?php
$searchQuery = $_GET['q'] ?? '';
echo '<input type="text" name="q" value="' . $searchQuery . '" />';
?>

Instead, it should sanitize the input, like this

<?php
$sanitized = htmlspecialchars($_GET['q'] ?? '', ENT_QUOTES, 'UTF-8');
echo '<input type="text" name="q" value="' . $sanitized . '" />';
?>

Malware or phishing code can be injected into the admin dashboard.

Note: Although this is in the admin panel, internal XSS is still a big deal, especially if attackers get access to a regular user account.

Original NVD Record:

CVE-2022-40487

ProcessWire Security Advisory:

https://processwire.com/about/news/ (search for CVE-related updates)
- Github Issue / Disclosure:  
 https://github.com/processwire/processwire-issues/issues/148

Upgrade ProcessWire:

Update to the latest stable version (anything newer than v3..200, ideally).

💡 Conclusion

CVE-2022-40487 shows how even backend/admin-only features can harbor dangerous XSS bugs. Never assume "internal" features are safe! Always keep your CMS updated, sanitize inputs, and review your codebase for similar issues.

If you run ProcessWire 3..200, upgrade immediately—and share this post with your team to help keep your site secure.

Timeline

Published on: 10/31/2022 12:15:00 UTC
Last modified on: 11/01/2022 17:32:00 UTC