CI4MS is a CodeIgniter 4-based content management system skeleton. Prior to version 0.31.9.0, the custom `html_purify` validation rule used to sanitize blog post bodies relies on by-reference mutation (`?string &$str`), but CodeIgniter 4's validator passes a local copy of the value, so the sanitized text is silently discarded. The Blog controller writes `$lanData['content']` directly into `blog_langs.content`, and the public template echoes it without escaping — yielding stored XSS executable in any visitor's browser, including the superadmin when previewing or editing posts. Version 0.31.9.0 patches the issue.