The official Vulnerability Notice is posted here : VN 2015 006 Symmetric Key NTPhttp://learn.extremenetworks.com/rs/extreme/images/VN-2015-006-NTP.pdf
and in article VN 2015 006 Symmetric Key NTPVulnerable : Yes
Vulnerable Component : NTP
Conditions : CVE-2015-1798->Authentication bypass vulnerability due to incorrect validation of mac field.
: CVE-2015-1799->Possible Dos attack due to incorrect state-variable updates upon receiving certain invalid packets.
Product version affected : All exos versions.
Workaround : No workaround is available, but system not running ntpd will be safe from this vulnerability. Risk of exploitation can be minimized by restricting ntp host access to trusted sources only.
Target Fix Release : Exos 16.2.1
Target Month : Jan 2016This does not affect SNTP