Cloudreve's remote download file paths can escape the selected destination directory

Summary

Cloudreve trusts file paths returned by the configured remote downloader. A downloader-reported path such as ../../escaped.txt can cause a downloaded file to be created outside the user-selected destination directory.

Details

In the remote download master transfer path, Cloudreve joins the user-selected destination URI with the downloader-reported file name.

// pkg/filemanager/workflows/remote_download.go:436-438
sanitizedName := sanitizeFileName(file.Name)
dst := dstUri.JoinRaw(sanitizedName)
src := filepath.FromSlash(path.Join(m.state.Status.SavePath, file.Name))