textpattern 4.8.7 is vulnerable to Cross Site Scripting (XSS) via /textpattern/index.php,Body. A remote and unauthenticated attacker can use XSS to trigger remote code execution by uploading a webshell. To do so they must first steal the CSRF token before submitting a file upload request.
https://pentest.co.uk/labs/leveraging-xss-to-get-rce-in-textpattern/