October is a self-hosted CMS platform based on the Laravel PHP Framework. The X-October-Request-Handler Header does not sanitize the AJAX handler name and allows unescaped HTML to be reflected back. There is no impact since this vulnerability cannot be exploited through normal browser interactions. This unescaped value is only detectable when using a proxy interception tool. This issue has been patched in version 3.5.15.

October System module has a Reflected XSS via X-October-Request-Handler Header