medium
5.9
CWE
362
Advisory Published
Updated

CVE-2016-4955: Race Condition

First published: Tue Jul 05 2016(Updated: )

ntpd in NTP 4.x before 4.2.8p8, when autokey is enabled, allows remote attackers to cause a denial of service (peer-variable clearing and association outage) by sending (1) a spoofed crypto-NAK packet or (2) a packet with an incorrect MAC value at a certain time.

Credit: cve@mitre.org

Affected SoftwareAffected VersionHow to fix
Siemens Simatic Net CP 443-1 OPC UA Firmware
NTP>=4.2.0<4.2.8
NTP>=4.3.0<4.3.93
NTP=4.2.8
NTP=4.2.8-p1
NTP=4.2.8-p1-beta1
NTP=4.2.8-p1-beta2
NTP=4.2.8-p1-beta3
NTP=4.2.8-p1-beta4
NTP=4.2.8-p1-beta5
NTP=4.2.8-p1-rc1
NTP=4.2.8-p1-rc2
NTP=4.2.8-p2
NTP=4.2.8-p2-rc1
NTP=4.2.8-p2-rc2
NTP=4.2.8-p2-rc3
NTP=4.2.8-p3
NTP=4.2.8-p3-rc1
NTP=4.2.8-p3-rc2
NTP=4.2.8-p3-rc3
NTP=4.2.8-p4
NTP=4.2.8-p5
NTP=4.2.8-p6
NTP=4.2.8-p7
Oracle Solaris and Zettabyte File System (ZFS)=10
Oracle Solaris and Zettabyte File System (ZFS)=11.3
SUSE Manager Proxy=2.1
openSUSE OpenStack Cloud=5
SUSE Manager=2.1
SUSE Linux=42.1
openSUSE=13.2
SUSE Linux Enterprise Desktop=12-sp1
SUSE Linux Enterprise Server=11-sp2
SUSE Linux Enterprise Server=11-sp3
SUSE Linux Enterprise Server=11-sp4
SUSE Linux Enterprise Server=12-sp1
siemens SIMATIC cp443-1 OPC UA firmware
Siemens Simatic Net CP 443-1 OPC UA Firmware

Remedy

http://support.ntp.org/bin/view/Main/NtpBug3043

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Reference Links

Parent vulnerabilities

(Appears in the following advisories)

Frequently Asked Questions

  • What is the severity of CVE-2016-4955?

    CVE-2016-4955 has a medium severity rating due to its potential to cause denial of service.

  • How do I fix CVE-2016-4955?

    To fix CVE-2016-4955, upgrade to NTP version 4.2.8p8 or later.

  • What systems are affected by CVE-2016-4955?

    CVE-2016-4955 affects NTP versions 4.2.0 through 4.2.8p7 and several Siemens devices.

  • What type of attack is associated with CVE-2016-4955?

    CVE-2016-4955 is associated with denial of service attacks caused by spoofed packets.

  • Is autokey enabled by default in versions affected by CVE-2016-4955?

    Yes, the vulnerability in CVE-2016-4955 occurs when autokey is enabled.

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