PHP Object Injection is a critical vulnerability that allows remote attackers to take control of a PHP application by manipulating serialized data. This occurs when user input is passed to the `unserialize()` function, which can lead to Remote Code Execution. The vulnerability exploits weaknesses in PHP's serialization and deserialization mechanisms, allowing attackers to inject malicious objects into memory. The payload format used for object injection is called "property-oriented programming" and has been exploited in various real-world attacks, including those on popular platforms like Pydio, WooCommerce, and PrestaShop. Understanding the risks of PHP Object Injection is crucial for securing PHP applications against such attacks.