InstantCMS version 2.16.1 suffers from a persistent cross site scripting vulnerability that appears to require administrative access.
# Exploit Title: InstantCMS - Store XSS
# Application: InstantCMS
# Version: v2.16.1
# Bugs: Stored XSS
# Technology: PHP
# Vendor Homepage: https://instantcms.ru/
# Software Link: https://instantcms.ru/get
# Date: 14.09.2023
# Author: SoSPiro
# Tested on: Windows
## Description
I noticed that you filtered the filter very carefully. But there are still some parts you missed
## POC
1 . Login with admin
2 . Go to "http://localhost/o2/admin/menu/item_edit/18"
3 . Insert payload in CSS class
4 . Click save , and go to home page, and Detect store xss in footer
https://drive.google.com/file/d/1_9QGoBnbZZrsHUgNkujja1Ptj3f8fl2W/view?usp=sharing
## Impact
This security vulnerability has the potential to steal multiple users' cookies, gain unauthorized access to that user's account through stolen cookies, or redirect the user to other malicious websites...
## Bug fix commit
https://github.com/instantsoft/icms2/commit/b2172a0f842fc28966b00bab3e2e9094c6bfd156
## Reference
https://huntr.com/bounties/18546c85-de6a-4252-a02f-c9d26f4f775e/
