Connect with us

Hi, what are you looking for?



High Severity DoS Vulnerability Patched in NTP

A new version of the Network Time Protocol daemon (ntpd) released last week by the NTP Project addresses several vulnerabilities, including a high severity issue introduced by a previous patch.

A new version of the Network Time Protocol daemon (ntpd) released last week by the NTP Project addresses several vulnerabilities, including a high severity issue introduced by a previous patch.

Ntp-4.2.8p8 resolves a total of five vulnerabilities. The most serious of them is CVE-2016-4957, a high severity denial-of-service (DoS) flaw that can be exploited to cause ntpd to crash.

The security hole was introduced by the fix for CVE-2016-1547, an issue patched in April after it was reported by Stephen Gray and Matthew Van Gundy of Cisco ASIG. CVE-2016-1547 is related to the processing of crypto NAK packets and it can be exploited by an off-path attacker to cause a preemptable client association to be demobilized.

The other vulnerabilities, reported to the NTP Project by Miroslav Lichvar and Jakub Prokes of Red Hat, have been rated as having low severity. They have been described as bad authentication demobilizes ephemeral associations (CVE-2016-4953), processing spoofed server packets (CVE-2016-4954), autokey association reset (CVE-2016-4955), and a broadcast interleave issue (CVE-2016-4956). CVE-2016-4956 is caused by an incomplete fix for a previously discovered flaw.

An advisory published by US-CERT shows that the products of many major vendors could be affected by these NTP vulnerabilities.

Red Hat has clarified that Red Hat Enterprise Linux is not affected by CVE-2016-4957 as the fix developed by the company for CVE-2016-1547 is different from the upstream patch.

Cisco has also published an advisory to inform customers that it’s currently trying to determine which of its products are affected by the NTP flaws. So far, the company has confirmed that one or more of these bugs affect some of its collaboration and social media, endpoint client, hosted services, network and content security, network management and provisioning, and network application, service and acceleration products.

Advertisement. Scroll to continue reading.

Researchers from Chinese security firm Qihoo 360 warned at the Hack in the Box (HITB) conference last month that remote attackers can wirelessly change the time on NTP servers over long distances using widely available, inexpensive devices.

Related: Several Vulnerabilities Patched in NTP Daemon

Written By

Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.

Click to comment

Daily Briefing Newsletter

Subscribe to the SecurityWeek Email Briefing to stay informed on the latest threats, trends, and technology, along with insightful columns from industry experts.

SecurityWeek’s Threat Detection and Incident Response Summit brings together security practitioners from around the world to share war stories on breaches, APT attacks and threat intelligence.


Securityweek’s CISO Forum will address issues and challenges that are top of mind for today’s security leaders and what the future looks like as chief defenders of the enterprise.


Expert Insights

Related Content


Less than a week after announcing that it would suspended service indefinitely due to a conflict with an (at the time) unnamed security researcher...

Data Breaches

OpenAI has confirmed a ChatGPT data breach on the same day a security firm reported seeing the use of a component affected by an...

Risk Management

The supply chain threat is directly linked to attack surface management, but the supply chain must be known and understood before it can be...


The latest Chrome update brings patches for eight vulnerabilities, including seven reported by external researchers.


Patch Tuesday: Microsoft warns vulnerability (CVE-2023-23397) could lead to exploitation before an email is viewed in the Preview Pane.


Apple has released updates for macOS, iOS and Safari and they all include a WebKit patch for a zero-day vulnerability tracked as CVE-2023-23529.

IoT Security

A group of seven security researchers have discovered numerous vulnerabilities in vehicles from 16 car makers, including bugs that allowed them to control car...

IoT Security

A vulnerability affecting Dahua cameras and video recorders can be exploited by threat actors to modify a device’s system time.