What potential security risks should be considered when allowing users to change their passwords in PHP applications?

When allowing users to change their passwords in PHP applications, it is important to consider potential security risks such as weak passwords, lack of password complexity requirements, and insufficient validation of the user's identity before allowing the password change. To mitigate these risks, you should enforce strong password policies, including minimum length, complexity requirements, and expiration periods. Additionally, always verify the user's identity before allowing a password change, such as requiring the user to enter their current password or sending a verification code to their email or phone.

// Validate the user's current password before allowing a password change
if ($_POST['current_password'] !== $user->password) {
    echo 'Current password is incorrect';
    exit;
}

// Enforce strong password policies
$new_password = $_POST['new_password'];
if (strlen($new_password) < 8 || !preg_match('/[A-Za-z]/', $new_password) || !preg_match('/\d/', $new_password)) {
    echo 'Password must be at least 8 characters long and contain letters and numbers';
    exit;
}

// Update the user's password in the database
$user->password = $new_password;
$user->save();