Exploit WordPress Plugin Live Chat Unlimited 2.8.3 - Cross-Site Scripting

# Exploit Title: Live Chat Unlimited v2.8.3 Stored XSS Injection
# Google Dork: inurl:"wp-content/plugins/screets-lcx"
# Date: 2019/06/25
# Exploit Author: m0ze
# Vendor Homepage: https://screets.com/
# Software Link: https://codecanyon.net/item/wordpress-live-chat-plugin/3952877
# Version: 2.8.3
# Tested on: Windows 10 / Parrot OS
# CVE : -


Info:

Weak security measures like bad input field data filtering has been
discovered in the «Live Chat Unlimited». Current version of this
premium WordPress plugin is 2.8.3.



PoC:

Go to the demo website https://site.com/try/lcx/night-bird/ and open chat window by clicking on «Open/close» link, then click on «Online mode» to go online. Use your payload inside input field and press [Enter]. 
Provided exaple payloads working on the admin area, so it's possible to steal admin cookies or force a redirect to any other
website.
Example #1: <!--<img src="--><img src=x onerror=(alert)(`m0ze`)//">m0ze
Example #2: <!--<img src="--><img src=x onerror=(alert)(document.cookie)//">m0ze