NTP BUG 2853: ntpd control message crash: Crafted NUL-byte in configuration directive

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

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Summary

Resolved	4.2.8p3	29 Jun 2015
References	Bug 2853	CVE-2015-5146
Affects	4.2.5p3 up to, but not including 4.2.8p3-RC1, and 4.3.0 up to, but not including 4.3.25.	Resolved in 4.2.8p3.
CVSS2 Score	4.9 at likely worst, 1.4 or less at likely best	AV:A/AC:M/Au:S/C:P/I:P/A:P

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Description

Under limited and specific circumstances an attacker can send a crafted packet to cause a vulnerable ntpd instance to crash. This requires each of the following to be true:

1. ntpd set up to allow for remote configuration (not allowed by default), and
2. knowledge of the configuration password, and
3. access to a computer entrusted to perform remote configuration.

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Mitigation

• Upgrade to 4.2.8p3 or later.
• Be prudent when deciding what IP addresses can perform remote configuration of an ntpd instance.
• Monitor your ntpd instances.

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Credit

This weakness was discovered by Aleksis Kauppinen of Codenomicon.

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Timeline

• 2015 Jun 29: Public release
• 2015 Jun 24: Early Access Program Release: Premier and Partner Institutional Members
• 2015 Jun 22: Notification to Institutional Members
• 2015 Jun 16: Notification received from FICORA; analysis begins