Flatpress Cross-site Scripting

Flatpress v1.2.1 was discovered to contain a reflected cross-site scripting (XSS) vulnerability via the page parameter at /flatpress/admin.php. (2022-10-11, CVE-2022-40047)

A stored cross-site scripting (XSS) vulnerability exists in FlatPress 1.2.1 that allows for arbitrary execution of JavaScript commands through blog content. (2022-06-23, CVE-2021-41432)

Flatpress v1.2.1 was discovered to contain a cross-site scripting (XSS) vulnerability in the Upload SVG File function. (2022-02-15, CVE-2022-24588)

FlatPress 1.0.3 is affected by cross-site scripting (XSS) in the Blog Content component. This vulnerability can allow an attacker to inject the XSS payload in Blog content via the admin panel. Each time any user will go to that blog page, the XSS triggers and the attacker can steal the cookie according to the crafted payload. (2020-12-30, CVE-2020-35241)

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>