GetPaid < 2.3.4 – Authenticated Stored XSS | CVE 2021-24369

Description

In the plugin, users with the contributor role and above can create a new Payment Form, however the Label and Help Text input fields were not getting sanitized properly. So it was possible to inject malicious content such as img tags, leading to a Stored Cross-Site Scripting issue which is triggered when the form will be edited, for example when an admin reviews it and could lead to privilege escalation.

Proof of Concept

https://www.youtube.com/watch?v=1VHJ0Ig80WM

Steps to reproduce:

1) Sign in with an Contributor Account

2) Create a Form and add <img src=x onerror=alert(1) /> to the Help Text or Field Label option of any field

3) The XSS will fire because of the live render. Discard this alert Box and post your Form for review

4) Sign in with your admin account and check the new form in the backend (like when reviewing it).

5) Observe the XSS

Impact: Every user with the contributor role can execute malicious javascript. This makes it possible to insert rogue admin accounts via the xss and take over the site