CVE-2016-2517

Severity: medium (CVSS 5.3 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 8.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2017-01-30 · updated 2026-06-17
Weakness: CWE-20

Description

NTP before 4.2.8p7 and 4.3.x before 4.3.92 allows remote attackers to cause a denial of service (prevent subsequent authentication) by leveraging knowledge of the controlkey or requestkey and sending a crafted packet to ntpd, which changes the value of trustedkey, controlkey, or requestkey. NOTE: this vulnerability exists because of a CVE-2016-2516 regression.

Affected products

NTP: through 4.2.8; 4.3.0, 4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.3.5 (+86)

References

http://support.ntp.org/bin/view/Main/NtpBug3010
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.securityfocus.com/bid/88189
http://www.securitytracker.com/id/1035705
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc
https://security.gentoo.org/glsa/201607-15
https://security.netapp.com/advisory/ntap-20171004-0002/
https://www.kb.cert.org/vuls/id/718152
http://support.ntp.org/bin/view/Main/NtpBug3010
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.securityfocus.com/bid/88189
http://www.securitytracker.com/id/1035705

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