CVE-2024-4023: Flatpress

High severity, CVSS 8.1. EPSS: 0.8% chance of exploitation in the next 30 days.

A stored cross-site scripting (XSS) vulnerability exists in flatpressblog/flatpress version 1.3. When a user uploads a file with a `.xsig` extension and directly accesses this file, the server responds with a Content-type of application/octet-stream, leading to the file being processed as an HTML file. This allows an attacker to execute arbitrary JavaScript code, which can be used to steal user cookies, perform HTTP requests, and access content of the same origin.

Affected products

Published 2025-03-20. Last modified 2026-06-17.