What are the potential security risks and vulnerabilities in the provided PHP login script?

One potential security risk in the provided PHP login script is the vulnerability to SQL injection attacks. To mitigate this risk, we should use prepared statements with parameterized queries to prevent malicious SQL injection attempts. 

// Original vulnerable code
$username = $_POST['username'];
$password = $_POST['password'];

$query = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$result = mysqli_query($conn, $query);

// Fixed code using prepared statements
$username = $_POST['username'];
$password = $_POST['password'];

$query = "SELECT * FROM users WHERE username=? AND password=?";
$stmt = mysqli_prepare($conn, $query);
mysqli_stmt_bind_param($stmt, "ss", $username, $password);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_get_result($stmt);

Keywords

SQL injection cross-site scripting password hashing session fixation CSRF protection

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