4.2.8p7 Release Announcement

Last update: September 3, 2026 14:42 UTC (1eec487e7)

NTF’s NTP Project has been notified of the following 4 low- and 7 medium-severity vulnerabilities that are fixed in ntp-4.2.8p7, released on Tuesday, 26 April 2016:

3020: Refclock impersonation vulnerability / CVE-2016-1551 AKA: refclock-peering
- Reported by Matt Street and others of Cisco ASIG
3012: Sybil vulnerability: ephemeral association attack / CVE-2016-1549 AKA: ntp-sybil - MITIGATION ONLY
- Reported by Matthew Van Gundy of Cisco ASIG
3011: Duplicate IPs on unconfig directives will cause an assertion botch / CVE-2016-2516
- Reported by Yihan Lian of the Cloud Security Team, Qihoo 360
3010: Remote configuration trustedkey/requestkey values are not properly validated / CVE-2016-2517
- Reported by Yihan Lian of the Cloud Security Team, Qihoo 360
3009: Crafted addpeer with hmode > 7 causes array wraparound with MATCH_ASSOC / CVE-2016-2518
- Reported by Yihan Lian of the Cloud Security Team, Qihoo 360
3008: ctl_getitem() return value not always checked / CVE-2016-2519
- Reported by Yihan Lian of the Cloud Security Team, Qihoo 360
3007: Validate crypto-NAKs / CVE-2016-1547 AKA: nak-dos
- Reported by Stephen Gray and Matthew Van Gundy of Cisco ASIG
2978: Interleave-pivot / CVE-2016-1548 - MITIGATION ONLY
- Reported by Miroslav Lichvar of RedHat and separately by Jonathan Gardner of Cisco ASIG
2952: KoD fix: peer associations were broken by the fix for 2901 / CVE-2015-7704 AKA: Symmetric active/passive mode is broken
- Reported by Michael Tatarinov, NTP Project Developer Volunteer
2945 / 2901: Zero Origin Timestamp Bypass / CVE-2015-8138 AKA: Additional KoD Checks
- Reported by Jonathan Gardner of Cisco ASIG
2879: Improve NTP security against buffer comparison timing attacks, authdecrypt-timing / CVE-2016-1550 AKA: authdecrypt-timing
- Reported independently by Loganaden Velvindron, and Matthew Van Gundy and Stephen Gray of Cisco ASIG.

The following issues already listed above are “Mitigation only” and are expected to be fully resolved in an upcoming release.

3012: Sybil vulnerability: ephemeral association attack - MITIGATION ONLY
2978: Interleave pivot - MITIGATION ONLY

The following issues were fixed in earlier releases and contain improvements in this p7 release:

Timeline:

2016 Apr 26: Public release
2016 Apr 18: CERT notified and pre-release patch availability announced to CERT
2016 Apr 12: Early Access Program Release: Premier and Partner Institutional Members
2016 Feb 21: CVE numbers requested from Mitre
2016 Feb 19: Initial notification from Qihoo/360; analysis begins
2016 Feb 14: Notification to Institutional Members
2016 Jan 12: Initial notification from Cisco; analysis begins