FlatPress contains a stored cross-site scripting vulnerability in comment and contact forms where name, URL, and email fields are rendered without proper output encoding in Smarty templates. Attackers can inject arbitrary HTML and JavaScript through these fields to execute malicious scripts in browsers of viewers including administrators, or bypass URL scheme validation to inject javascript: or data: URIs.

A stored Cross-Site Scripting (XSS) vulnerability was identified in FlatPress 1.3.1 within the "Add Entry" feature. This vulnerability allows authenticated attackers to inject malicious JavaScript payloads into blog posts, which are executed when other users view the posts. The issue arises due to improper input sanitization of the "TextArea" field in the blog entry submission form.

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

Flatpress v1.2.1 was discovered to contain a remote code execution (RCE) vulnerability in the Upload File function.