(RHSA-2009:1039) Important: ntp security update

The Network Time Protocol (NTP) is used to synchronize a computer’s time
with a referenced time source.

A buffer overflow flaw was discovered in the ntpd daemon’s NTPv4
authentication code. If ntpd was configured to use public key cryptography
for NTP packet authentication, a remote attacker could use this flaw to
send a specially-crafted request packet that could crash ntpd.
(CVE-2009-1252)

Note: NTP authentication is not enabled by default.

A buffer overflow flaw was found in the ntpq diagnostic command. A
malicious, remote server could send a specially-crafted reply to an ntpq
request that could crash ntpq. (CVE-2009-0159)

All ntp users are advised to upgrade to this updated package, which
contains backported patches to resolve these issues. After installing the
update, the ntpd daemon will be restarted automatically.