Grav before 2.0.15 contains a path traversal vulnerability in the static asset server within index.php that uses string prefix matching instead of directory-boundary validation. Unauthenticated attackers can access files in sibling directories by exploiting directory names that extend the base path string, such as requesting assets-secret when assets is the configured base.

Grav: Unauthenticated Path Traversal via Missing Directory-Boundary Check in `plugin-asset-map.php` Static Asset Server (`index.php`)