    def _dump(self, file=None, format=None):
        import tempfile
        if not file:
            file = tempfile.mktemp()
        self.load()
        if not format or format == "PPM":
            self.im.save_ppm(file)
        else:
            file = file + "." + format
            self.save(file, format)
        return file
The software attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.