{"id":"UBUNTU-CVE-2016-1547","details":"An off-path attacker can cause a preemptible client association to be demobilized in NTP 4.2.8p4 and earlier and NTPSec a5fb34b9cc89b92a8fef2f459004865c93bb7f92 by sending a crypto NAK packet to a victim client with a spoofed source address of an existing associated peer. This is true even if authentication is enabled.","modified":"2026-02-04T02:55:06.801661Z","published":"2016-04-29T00:00:00Z","related":["USN-3096-1"],"upstream":["CVE-2016-1547"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2016-1547"},{"type":"REPORT","url":"http://support.ntp.org/bin/view/Main/SecurityNotice#April_2016_NTP_4_2_8p7_Security"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-3096-1"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2016-1547"}],"affected":[{"package":{"name":"ntp","ecosystem":"Ubuntu:14.04:LTS","purl":"pkg:deb/ubuntu/ntp@1:4.2.6.p5+dfsg-3ubuntu2.14.04.10?arch=source&distro=trusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:4.2.6.p5+dfsg-3ubuntu2.14.04.10"}]}],"versions":["1:4.2.6.p5+dfsg-3ubuntu2","1:4.2.6.p5+dfsg-3ubuntu2.14.04.1","1:4.2.6.p5+dfsg-3ubuntu2.14.04.2","1:4.2.6.p5+dfsg-3ubuntu2.14.04.3","1:4.2.6.p5+dfsg-3ubuntu2.14.04.5","1:4.2.6.p5+dfsg-3ubuntu2.14.04.6","1:4.2.6.p5+dfsg-3ubuntu2.14.04.7","1:4.2.6.p5+dfsg-3ubuntu2.14.04.8"],"ecosystem_specific":{"binaries":[{"binary_version":"1:4.2.6.p5+dfsg-3ubuntu2.14.04.10","binary_name":"ntp"},{"binary_version":"1:4.2.6.p5+dfsg-3ubuntu2.14.04.10","binary_name":"ntpdate"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2016/UBUNTU-CVE-2016-1547.json"}},{"package":{"name":"ntp","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/ntp@1:4.2.8p4+dfsg-3ubuntu5.3?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:4.2.8p4+dfsg-3ubuntu5.3"}]}],"versions":["1:4.2.6.p5+dfsg-3ubuntu8","1:4.2.6.p5+dfsg-3ubuntu8.1","1:4.2.6.p5+dfsg-3ubuntu9","1:4.2.8p4+dfsg-3ubuntu1","1:4.2.8p4+dfsg-3ubuntu2","1:4.2.8p4+dfsg-3ubuntu3","1:4.2.8p4+dfsg-3ubuntu4","1:4.2.8p4+dfsg-3ubuntu5","1:4.2.8p4+dfsg-3ubuntu5.1","1:4.2.8p4+dfsg-3ubuntu5.2"],"ecosystem_specific":{"binaries":[{"binary_version":"1:4.2.8p4+dfsg-3ubuntu5.3","binary_name":"ntp"},{"binary_version":"1:4.2.8p4+dfsg-3ubuntu5.3","binary_name":"ntpdate"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2016/UBUNTU-CVE-2016-1547.json"}}],"schema_version":"1.7.3","severity":[{"type":"CVSS_V3","score":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},{"type":"Ubuntu","score":"medium"}]}