NTP is a set of the Network Time Protocol programs.
Robin Park and Dmitri Vinokurov discovered that ntp_request.c in ntpd does not handle MODE_PRIVATE packets correctly, causing a continuous exchange of MODE_PRIVATE error responses between two NTP daemons or causing high CPU load on a single host.
A remote, unauthenticated attacker could send a specially crafted MODE_PRIVATE packet, allowing for a Denial of Service condition (CPU and bandwidth consumption).
There is no known workaround at this time.
All NTP users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=net-misc/ntp-4.2.4_p7-r1"