The following flaw was found in ntpd:
If ntpd was expressly configured to allow for remote configuration, a malicious user who knows the controlkey for ntpq or the requestkey for ntpdc (if mode7 is expressly enabled) can create a session with ntpd and then send a crafted packet to ntpd that will change the value of the trustedkey, controlkey, or requestkey to a value that will prevent any subsequent authentication with ntpd until ntpd is restarted.
Created ntp tracking bugs for this issue:
Affects: fedora-all [bug 1332160]
Red Hat Product Security does not consider this to be a security issue. An authenticated user could use various other means to disable access to an NTP server (for example, using the 'restrict' command). To mitigate this issue, disable remote configuration of NTP, or restrict this ability to trusted users.