SABnzbd: Orphan-job path traversal permits arbitrary file deletion

SABnzbd is an open source automated Usenet download tool. Prior to 5.1.0Beta3, orphan-job management in sabnzbd/api.py accepts the user-controlled value parameter without path confinement before os.path.join() with download_dir. An absolute path discards that base directory. An attacker with a valid API key can invoke mode=status with name=delete_orphan to reach _api_delete_orphan and remove_all() in sabnzbd/filesystem.py, which uses shutil.rmtree() for recursive deletion. The advisory also identifies _api_add_orphan and _api_delete_all_orphan as affected by the path-validation issue, while its concrete arbitrary-deletion trace is through _api_delete_orphan. The API key is stored in plaintext in sabnzbd.ini. The attacker can delete files or directories writable by the SABnzbd process, including configuration, queue data, and downloads, but system files outside the regular user's ownership are not affected. This issue is fixed in version 5.1.0Beta3.