A Denial of Service (DoS) vulnerability was discovered in the network time protocol server/client, ntp.
ntp allowed an “off-path” attacker to block unauthenticated synchronisation via a server mode packet with a spoofed source IP address because transmissions were rescheduled even if a packet lacked a valid “origin timestamp”.
For Debian 7 Wheezy, these problems have been fixed in version 1:4.2.6.p5+dfsg-2+deb7u8.
We recommend that you upgrade your ntp packages.
Further information about Extended LTS security advisories can be found at: https://deb.freexian.com/extended-lts/