ntpd-rs is a full-featured implementation of the Network Time Protocol. Prior to 1.7.1, an attacker can remotely induce moderate increases (2-4 times above normal) in cpu usage. When having NTS enabled on an ntpd-rs server, an attacker can create malformed NTS packets that take significantly more effort for the server to respond to by requesting a large number of cookies. This can lead to degraded server performance even when a server could otherwise handle the load. This vulnerability is fixed in 1.7.1.