Swift Prometheus is a Swift client for the Prometheus monitoring system, supporting counters, gauges and histograms. In code which applies un-sanitized string values into metric names or labels, an attacker could make use of this and send a "?lang" query parameter containing newlines, "}" or similar characters which can lead to the attacker taking over the exported format -- including creating unbounded numbers of stored metrics, inflating server memory usage, or causing "bogus" metrics. This vulnerability is fixed in2.0.0-alpha.2.