MyBB Thread Redirect Plugin 0.2.1 - Cross-Site Scripting

# Exploit Title: MyBB Thread Redirect Plugin 0.2.1 - Cross-Site Scripting
# Date: 7/23/2018
# Author: 0xB9
# Software Link: https://github.com/jamiesage123/Thread-Redirect
# Version: 0.2.1
# Tested on: Windows 10

1. Description:
This plugin allows threads to redirect to a URL with optional custom text. The custom text input is vulnerable to Cross-Site Scripting.

2. Proof of Concept:

- Create a new thread
- Input any Thread Subject and Redirect URL you'd like
- Use the following payload for Your Message     <svg/onload=alert('XSS')>
Anyone who views the thread will execute payload.