A Path Traversal vulnerability in AllSky v2023.05.01_04 allows an unauthenticated attacker to create a webshell and remote code execution via the path, content parameter to /includes/save_file.php.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.