How can the use of variables like $_POST['name'] and $_POST['vorname'] in PHP forms lead to security vulnerabilities?

Using variables like $_POST['name'] and $_POST['vorname'] directly in PHP forms can lead to security vulnerabilities such as SQL injection and cross-site scripting attacks. To prevent this, it is important to sanitize and validate user input before using it in your application. This can be done by using functions like htmlspecialchars() to escape special characters and prevent malicious code execution.

$name = htmlspecialchars($_POST['name']);
$vorname = htmlspecialchars($_POST['vorname']);