Update - 5/10/2023

The CVE-2023-2123 ID was reserved and the PoC was published in the WPScan website: https://wpscan.com/vulnerability/44448888-cd5d-482e-859e-123e442ce5c1

Details

Title: Unauthenticated Reflected Cross-Site Scripting in WP Inventory Manager Plugin for WordPress CMS
Date: 2023-04-15
Author: Danilo Albuquerque
Vendor Homepage: https://wordpress.org
Software Link: https://wordpress.org/download
Version: WordPress 6.2
Plugin's Name and Version: WP Inventory Manager 2.1.0.12
Tested on: Brave (Version 1.50.119 Chromium: 112.0.5615.121 (Official Version) 64 bits)

PoC for Reflected XSS vulnerability in WP Inventory Manager 2.1.0.12

1. Go to the page that has the inventory items;
2. Access the item that you want;
3. Fill the form in the "Reserve This Item" section of the page and click on "Reserve" button;
4. Once you have been redirected to the "Your reservation has been submited" page, add the ENCODED payload %3Cscript%3Ealert%281%29%3C%2Fscript%3E in the message parameter in the URL;
5. Press enter to do the request and voilá.

When you do all that and update the current page, it will bring you the alert pop-up with the message in it.

Screenshots below

1. Go to the page that has the inventory items:
   

2. Access the item that you want:
   

3. Fill the form in the "Reserve This Item" section of the page and click on "Reserve" button:
   

4. Once you have been redirected to the "Your reservation has been submited" page, add the ENCODED payload %3Cscript%3Ealert%281%29%3C%2Fscript%3E in the message parameter in the URL:
   

5.The alert pop-up:

Bonus

You can also add a DOUBLE ENCODED malicious payload, and the attacker will be able to bypass some security controls such as not accept quotes.

The payload I used: %253Cscript%253Ealert%2528%2522pwned%2520by%2520daniloalbuqrque%2522%2529%253C%252Fscript%253E

Screenshot below: