Calculated Fields Form < 1.1.151 – Admin+ Stored Cross-Site Scripting via Dropdown Fields | CVE 2023-0389

Description

The plugin does not sanitise and escape some of its form settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup)

Partial fixes were implemented in versions 1.1.148, 1.1.150, and 1.1.151.

Proof of Concept

The following steps work on version 1.1.147, before any partial fixes.

1. Go to the "Calculated Fields Form" page in WP Admin.
2. Under "New Form", add an "Item Name" and choose "From Template".
3. Choose the template "DropDown fields with Images" and click "Use It".
4. Click on the first field (`fieldname1`) and in the Field Settings sidebar on the left, change the `Text` field on one of the choices to `<img src="x" onerror=alert(/XSS/)>`.
5. After saving , either preview the Form, or view a post/page with the form embed to trigger the XSS