CVE-2015-7691: Input Validation
It was found that the fix for CVE-2014-9750 was incomplete: three issues were found in the value length checks in ntpcrypto.c, where a packet with particular autokey operations that contained malicious data was not always being completely validated. Receipt of these packets can cause ntpd to crash.
Upstream patch:
https://github.com/ntp-project/ntp/commit/c4cd4aaf418f57f7225708a93bf48afb2bc9c1da
Mitigation:
Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.
External References:
https://github.com/ntp-project/ntp/blob/stable/NEWS#L11 http://support.ntp.org/bin/view/Main/SecurityNotice#October2015NTPSecurityVulner
Other sources
The cryptoxmit function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (crash) via crafted packets containing particular autokey operations. NOTE: This vulnerability exists due to an incomplete fix for CVE-2014-9750.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2015-7691?
CVE-2015-7691 has a moderate severity level, impacting the integrity of NTP packets.
How do I fix CVE-2015-7691?
To fix CVE-2015-7691, upgrade the NTP software to version 4.2.8 or higher.
Which software versions are affected by CVE-2015-7691?
CVE-2015-7691 affects NTP versions prior to 4.2.8, including versions between 4.2.0 and 4.3.77.
What type of vulnerability is CVE-2015-7691?
CVE-2015-7691 is a cryptographic vulnerability that involves improper handling of packet length checks.
Is CVE-2015-7691 associated with specific operating systems?
Yes, CVE-2015-7691 impacts various operating systems running affected versions of NTP, including Red Hat and Debian.