Admidio: Path Traversal via Unvalidated `name` Parameter in Document Add Mode Enables Arbitrary Server File Read

Admidio is an open-source user management solution. Prior to version 5.0.9, 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. This issue has been patched in version 5.0.9.