CVE-2016-2517
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…
Does this matter?
Lower severity and a low EPSS score (8.82%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.0
- 5.3 MEDIUMCVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 8.82% probability · 95th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-20
- Affected
- ntp/ntp
- Source
- cve@mitre.org
EPSS moved from 7.5% on 21 September 2026 to 8.8% on 26 October 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
References
- http://support.ntp.org/bin/view/Main/NtpBug3010Vendor Advisory
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.htmlThird Party Advisory
- http://www.securityfocus.com/bid/88189Third Party Advisory, VDB Entry
- 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/718152Third Party Advisory, US Government Resource
- http://support.ntp.org/bin/view/Main/NtpBug3010Vendor Advisory
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.htmlThird Party Advisory
- http://www.securityfocus.com/bid/88189Third Party Advisory, VDB Entry
- 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/718152Third Party Advisory, US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.