Network Time Protocol Daemon (ntpd) Security Notice

Number: AV16-091
Date: 3 June 2016


The purpose of this advisory is to bring attention to a Security Notice for Network Time Protocol Daemon (ntpd).


CCIRC is aware of vulnerabilities (1 high, 4 low) in the Network Time Protocol Daemon (ntpd) which if exploited, could allow a remote unauthenticated attacker to cause a denial-of-service condition in ntpd.

Affected versions: ntpd versions prior to 4.2.8p8

CVE References:  CVE-2016-4953, CVE-2016-4954, CVE-2016-4955, CVE-2016-4956, CVE-2016-4957

Suggested Action

CCIRC recommends that system administrators identify their affected assets and potential interdependencies with their organization’s critical services, and follow their patch management process accordingly or consider applying the workarounds.


NTP Security Notice - June 2016 ntp-4.2.8p8 NTP:

CERT/CC Vulnerability Note 321640:

Note to Readers

In support of Public Safety's mission to build a safe and resilient Canada, CCIRC's mandate is to help ensure the security and resilience of the vital non-federal government cyber systems that underpin Canada's national security, public safety and economic prosperity. As Canada's computer security incident response team, CCIRC is Canada's national coordination centre for the prevention and mitigation of, preparedness for, response to, and recovery from cyber incidents on non-federal government systems. It does this by providing authoritative advice and support, and coordinating information sharing and incident response.

Please note, CCIRC PGP key has recently been updated.

For general information, please contact Public Safety Canada's Public Affairs division at:

Telephone: 613-944-4875 or 1-800-830-3118
Fax: 613-998-9589

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