ntpd up to 4.2.8p7 Synchronization data processing

CVSS Meta Temp Score
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CTI Interest Score
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A vulnerability, which was classified as critical, was found in ntpd up to 4.2.8p7 (Network Management Software). This affects an unknown functionality of the component Synchronization. The manipulation with an unknown input leads to a data processing vulnerability. CWE is classifying the issue as CWE-19. This is going to have an impact on availability. The summary by CVE is:

ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (interleaved-mode transition and time change) via a spoofed broadcast packet. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-1548.

The weakness was presented 06/02/2016 by Miroslav Lichvar with Red Hat as confirmed release notes (Website). The advisory is shared at support.ntp.org. The public release was coordinated in cooperation with the project team. This vulnerability is uniquely identified as CVE-2016-4956 since 05/23/2016. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Neither technical details nor an exploit are publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 91662 (SUSE SLED12 / SLES12 Security Update : ntp (SUSE-SU-2016:1563-1)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family SuSE Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 371401 (Cisco UCS 6200 Series Fabric Interconnects Multiple Vulnerabilities in Network Time Protocol Daemon (CSCuz92668)).

Applying the patch 4.2.8p8 is able to eliminate this problem. A possible mitigation has been published before and not just after the disclosure of the vulnerability. The release notes contains the following remark:

NTP Consortium members at the Partner and Premier levels received pre-release patch access.

The vulnerability is also documented in the databases at Tenable (91662), SecurityFocus (BID 91009†) and SecurityTracker (ID 1036037†). Further details are available at kb.cert.org.






CPE 2.3info

CPE 2.2info


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VulDB Meta Base Score: 7.2
VulDB Meta Temp Score: 7.0

VulDB Base Score: 8.6
VulDB Temp Score: 8.2
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NVD Base Score: 5.8
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Class: Data processing

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

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Nessus ID: 91662
Nessus Name: SUSE SLED12 / SLES12 Security Update : ntp (SUSE-SU-2016:1563-1)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
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OpenVAS ID: 862576
OpenVAS Name: SuSE Update for ntp SUSE-SU-2016:1568-1 (ntp)
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Qualys ID: 🔍
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Threat Intelligenceinfo

Interest: 🔍
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Recommended: Patch
Status: 🔍

0-Day Time: 🔍

Patch: 4.2.8p8


05/23/2016 🔍
05/24/2016 +1 days 🔍
05/24/2016 +0 days 🔍
06/02/2016 +9 days 🔍
06/02/2016 +0 days 🔍
06/06/2016 +4 days 🔍
06/06/2016 +0 days 🔍
06/17/2016 +11 days 🔍
07/04/2016 +17 days 🔍
08/23/2022 +2241 days 🔍


Advisory: USN-3096-1
Researcher: Miroslav Lichvar
Organization: Red Hat
Status: Confirmed
Confirmation: 🔍
Coordinated: 🔍

CVE: CVE-2016-4956 (🔍)
SecurityFocus: 91009 - NTP CVE-2016-4956 Incomplete Fix Denial of Service Vulnerability
SecurityTracker: 1036037

Misc.: 🔍


Created: 06/06/2016 04:09 PM
Updated: 08/23/2022 08:07 AM
Changes: 06/06/2016 04:09 PM (76), 01/06/2019 10:27 AM (14), 08/23/2022 08:07 AM (3)
Complete: 🔍
Cache ID: 100:EBF:40


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