Updated ntp packages fix security vulnerabilities:

If no authentication key is defined in the ntp.conf file, a
cryptographically-weak default key is generated (CVE-2014-9293).

ntp-keygen before 4.2.7p230 uses a non-cryptographic random number
generator with a weak seed to generate symmetric keys (CVE-2014-9294).

A remote unauthenticated attacker may craft special packets that
trigger buffer overflows in the ntpd functions crypto_recv() (when
using autokey authentication), ctl_putdata(), and configure(). The
resulting buffer overflows may be exploited to allow arbitrary
malicious code to be executed with the privilege of the ntpd process
(CVE-2014-9295).

A section of code in ntpd handling a rare error is missing a return
statement, therefore processing did not stop when the error was
encountered. This situation may be exploitable by an attacker
(CVE-2014-9296).

The ntp package has been patched to fix these issues.