What potential pitfalls should be considered when passing variables between PHP forms?

One potential pitfall when passing variables between PHP forms is the risk of injection attacks if user input is not properly sanitized. To mitigate this risk, always use PHP functions like htmlspecialchars() or mysqli_real_escape_string() to sanitize user input before passing it between forms. Additionally, be cautious of sensitive information being exposed if variables are not properly scoped or validated. 

// Example of sanitizing user input before passing it between forms
$name = htmlspecialchars($_POST['name']);
$email = htmlspecialchars($_POST['email']);
```
```php
// Example of validating and scoping variables before passing between forms
if(isset($_POST['submit'])){
    $username = htmlspecialchars($_POST['username']);
    $password = htmlspecialchars($_POST['password']);
    
    // Validate username and password
    if(!empty($username) && !empty($password)){
        // Proceed with passing variables between forms
    } else {
        echo "Please fill out all fields.";
    }
}

Keywords

security vulnerabilities form validation session hijacking cross-site scripting data sanitization

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