The host is installed with ntp version 4.2.6 and earlier on Redhat Enterprise Linux 6 or on Redhat Enterprise Linux 7 and is prone to an endless loop vulnerability. A flaw is present in the application, which fails to handle MD5 symmetric keys on big-endian systems. Successful exploitation could allow attackers to guess generated MD5 keys that could then be used to spoof an NTP client or server.