MyBB Latest Posts on Profile Plugin 1.1 - Cross-Site Scripting

# Exploit Title: MyBB Latest Posts on Profile Plugin v1.1 - Cross-Site Scripting
# Date: 4/20/2018
# Author: 0xB9
# Contact: luxorforums.com/User-0xB9 or 0xB9[at]pm.me
# Software Link: https://community.mybb.com/mods.php?action=view&pid=914
# Version: 1.1
# Tested on: Ubuntu 17.10
# CVE: CVE-2018-10580


1. Description:
Adds a new section to user profiles that will display their last posts.
 

2. Proof of Concept:

Persistent XSS
- Create a thread with the following subject <script>alert('XSS')</script>
- Now visit your profile to see the alert.


3. Solution:
I reported the plugin twice over the past 3 weeks and recieved no response.


The following should be added in line 236 to properly sanitize thread subjects.

$d['tsubject'] = htmlspecialchars_uni($d['tsubject']);