CVE-2026-41656: Admidio has Path Traversal via Unvalidated `name` Parameter in Document Add Mode that Enables Arbitrary Server File Read

The add mode in modules/documents-files.php accepts a name parameter validated only as 'string' type (HTML encoding), allowing path traversal characters (../) to pass through unfiltered. Combined with the absence of CSRF protection on this endpoint and SameSite=Lax session cookies, a low-privileged attacker can trick a documents administrator into clicking a crafted link that registers an arbitrary server file (e.g., install/config.php containing database credentials) into a documents folder accessible to the attacker.