src/Helper.php
public static function hostCheck(string $host = null) : bool
    {
        if (!$host) {
            $host = (string)$_SERVER['HTTP_HOST'];
        }

        return getenv(static::DOMAIN_ENV_LABEL) !== false
            && strrpos(strrev($host), strrev('.' . getenv(static::DOMAIN_ENV_LABEL))) === 0;
    }
public static function hostCheck(string $host = null) : bool
    {
        if (!$host) {
            $host = (string)$_SERVER['HTTP_HOST'];
        }

        return getenv(static::DOMAIN_ENV_LABEL) !== false
            && strrpos(strrev($host), strrev('.' . getenv(static::DOMAIN_ENV_LABEL))) === 0;
    }
Проверка хоста, например, $_SERVER['HTTP_HOST'] на уязвимость.
Подробнее на https://expressionengine.com/blog/http-host-and-server-name-security-issues

@param string $host

@return bool