MyBB Threads To Link 1.3 Cross Site Scripting

`# Exploit Title: MyBB Threads to Link Plugin v1.3 - Persistent XSS  
# Date: 3/15/2018  
# Author: 0xB9  
# Contact: luxorforums.com/User-0xB9 or 0xB9[at]protonmail.com  
# Software Link: https://community.mybb.com/mods.php?action=view&pid=1065  
# Version: v1.3  
# Tested on: Ubuntu 17.10  
  
  
1. Description:  
When editing a thread the user is given to the option to convert the thread to a link.  
  
  
2. Proof of Concept:  
  
Persistent XSS  
- Edit a thread or post you've made  
- At the bottom of the edit page in the Thread Link box input the following <a """><SCRIPT>alert("XSS")</SCRIPT>">  
- Now visit the forum your thread/post exists in to see the alert.  
  
  
3. Solution:  
The plugin has since been removed after notifying the author.  
  
Patch in line 83:  
$thread['tlink'] = ($thread['tlink']);  
  
to  
  
$thread['tlink'] = htmlspecialchars_uni($thread['tlink']);  
`