Admin Columns Cross-site Scripting

The Admin Columns WordPress plugin Free before 4.3.2 and Pro before 5.5.2 allowed to configure individual columns for tables. Each column had a type. The type "Custom Field" allowed to choose an arbitrary database column to display in the table. There was no escaping applied to the contents of "Custom Field" columns. (2021-07-12, CVE-2021-24365)

The Admin Columns Free WordPress plugin before 4.3 and Admin Columns Pro WordPress plugin before 5.5.1, rendered input on the posted pages with improper input validation on the value passed into the field 'Label' parameter, by taking this as an advantage an authenticated attacker can supply a crafted arbitrary script and execute it. (2021-06-21, CVE-2021-24366)

Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.

The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:

https://server.com/confirmation?message=Transaction+Complete

what results in:

<span>Confirmation: Transaction Complete</span>

In that case the message can be modified to become a valid Javascript code, e.g.:

https://server.com/confirmation?message=<script>dangerous javascript code here</script>

and it will be executed locally by the user's browser with full access to the user's personal application/browser data:

<span>Confirmation: <script>dangerous javascript code here</script></span>