NTP before 4.2.8p6 and 4.3.x before 4.3.90, when configured in broadcast mode, allows man-in-the-middle attackers to conduct replay attacks by sniffing the network.
https://www.kb.cert.org/vuls/id/718152
https://us-cert.cisa.gov/ics/advisories/icsa-21-103-11
https://security.netapp.com/advisory/ntap-20171031-0001/
https://security.gentoo.org/glsa/201607-15
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:09.ntp.asc
https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03766en_us
https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03750en_us
https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf
https://bto.bluecoat.com/security-advisory/sa113
http://www.ubuntu.com/usn/USN-3096-1
http://www.securitytracker.com/id/1034782
http://www.securityfocus.com/bid/81963
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160127-ntpd