CVE-2015-1799

A denial of service flaw was found in the way NTP hosts that were peering with each other authenticated themselves before updating their internal state variables. An attacker could send packets to one peer host, which could cascade to other peers, and stop the synchronization process among the reached peers.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To work around this issue, instead of configuring NTP hosts as peers with the 'peer' directive, use the 'server' directive on both hosts so that the connection uses a regular client/server mode of operation.

More information about how to configure NTP can be found at:

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/ch-Configuring_NTP_Using_ntpd.html

Autokey authentication between NTP peers is not sufficient to fully mitigate this issue.