What are some potential security risks associated with using unescaped user input in PHP code, as seen in the provided example?

Using unescaped user input in PHP code can lead to security vulnerabilities such as SQL injection attacks, cross-site scripting (XSS), and command injection. To mitigate these risks, it is crucial to properly sanitize and escape user input before using it in database queries, output to the browser, or executing system commands. 

// Example of properly escaping user input before using it in a SQL query
$userInput = $_POST['username'];
$escapedInput = mysqli_real_escape_string($connection, $userInput);

$query = "SELECT * FROM users WHERE username='$escapedInput'";
$result = mysqli_query($connection, $query);

// Example of properly escaping user input before outputting it to the browser
$userInput = $_POST['comment'];
$escapedInput = htmlspecialchars($userInput);

echo "Your comment: " . $escapedInput;

Keywords

SQL injection cross-site scripting (XSS) htmlspecialchars htmlentities prepared statements

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