ntp -- control message remote Denial of Service vulnerability

ntp.org reports:

Under limited and specific circumstances an attacker can send a crafted packet to cause a vulnerable ntpd instance to crash. This requires each of the following to be true:

• ntpd set up to allow for remote configuration (not allowed by default), and
• knowledge of the configuration password, and
• access to a computer entrusted to perform remote configuration.

[source]