i need help please , i have a site with joomla but the URLs accept inyection just befor the www

i have a web site with joomla CMS , but i have a very BIG PROBLEM , when i acces to my site , with any number or caracter example : https://55.www.mysite.com or if i write any other caracter before the www. like this example : https://ddd.mysite.com , and the site work and generate a duplicated content , in th html code to , the canonical url is not the original... and that is duplicated content , i need help please...