CVE-2015-7853

The datalen parameter in the refclock driver in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to execute arbitrary code or cause a denial of service (crash) via a negative input value.

Published: 2017-08-07 Last update: 2026-05-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2015-7853 is rated High Risk (67.6/100): CVSS Critical severity, with high exploitation likelihood (EPSS 11.78%, 96th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2015-7853

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 39.59% 11.78% -27.81%
2 2026-05-21 40.56% 39.59% -0.98%
3 2026-05-01 — 40.56% —

Full EPSS history (23 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2015-7853

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2015-7853

OS Trackers for CVE-2015-7853

vendor priority summary link
debian not yet assigned CVE-2015-7853 not yet assigned priority: Debian including 1 source packages (ntp), 1 status rows across 1 suites (bullseye): resolved 1. https://security-tracker.debian.org/tracker/CVE-2015-7853
gentoo normal CVE-2015-7853: 1 GLSA(s) (201607-15), 1 atom(s) (net-misc/ntp); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2015-7853
redhat medium — https://access.redhat.com/security/cve/CVE-2015-7853
ubuntu medium CVE-2015-7853 medium priority: Ubuntu including 1 source packages (ntp), 5 status rows across 5 suites (precise, trusty, upstream, vivid, wily): released 4, needs-triage 1. https://ubuntu.com/security/CVE-2015-7853

Affected software / configurations for CVE-2015-7853

Vendor Product Version Raw CPE
ntp ntp >= 4.2.0, < 4.2.8 cpe:2.3:a:ntp:ntp:*:*:*:*:*:*:*:*
ntp ntp >= 4.3.0, < 4.3.77 cpe:2.3:a:ntp:ntp:*:*:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:-:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta3:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta4:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta5:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-rc1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-rc2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2-rc1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2-rc2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2-rc3:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p3:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p3-rc1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p3-rc2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p3-rc3:*:*:*:*:*:*
netapp oncommand_balance — cpe:2.3:a:netapp:oncommand_balance:-:*:*:*:*:*:*:*
netapp oncommand_performance_manager — cpe:2.3:a:netapp:oncommand_performance_manager:-:*:*:*:*:*:*:*
netapp oncommand_unified_manager — cpe:2.3:a:netapp:oncommand_unified_manager:-:*:*:*:*:clustered_data_ontap:*:*
netapp clustered_data_ontap — cpe:2.3:o:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*
netapp data_ontap — cpe:2.3:o:netapp:data_ontap:-:*:*:*:*:7-mode:*:*

References for CVE-2015-7853

URL Tags
http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00020.html
http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00048.html
http://lists.opensuse.org/opensuse-security-announce/2016-07/msg00026.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00042.html
http://lists.opensuse.org/opensuse-updates/2015-11/msg00093.html
http://lists.opensuse.org/opensuse-updates/2016-05/msg00114.html
http://packetstormsecurity.com/files/134082/FreeBSD-Security-Advisory-ntp-Authentication-Bypass.html
http://packetstormsecurity.com/files/134137/Slackware-Security-Advisory-ntp-Updates.html
http://support.ntp.org/bin/view/Main/NtpBug2920 Patch Vendor Advisory
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151021-ntp
http://www.securityfocus.com/archive/1/536737/100/0/threaded
http://www.securityfocus.com/archive/1/536760/100/0/threaded
http://www.securityfocus.com/archive/1/536796/100/0/threaded
http://www.securityfocus.com/archive/1/536833/100/0/threaded
http://www.securityfocus.com/archive/1/archive/1/536737/100/100/threaded
http://www.securityfocus.com/archive/1/archive/1/536760/100/100/threaded
http://www.securityfocus.com/archive/1/archive/1/536796/100/100/threaded
http://www.securityfocus.com/archive/1/archive/1/536833/100/100/threaded
http://www.securityfocus.com/bid/77273 Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1033951 Third Party Advisory VDB Entry
http://www.talosintel.com/vulnerability-reports/
http://www.ubuntu.com/usn/USN-2783-1
https://bto.bluecoat.com/security-advisory/sa103
https://bugzilla.redhat.com/show_bug.cgi?id=1274262 Issue Tracking Third Party Advisory VDB Entry
https://cert-portal.siemens.com/productcert/pdf/ssa-211752.pdf
https://security.gentoo.org/glsa/201607-15 Third Party Advisory VDB Entry
https://security.netapp.com/advisory/ntap-20171004-0001/ Third Party Advisory
https://us-cert.cisa.gov/ics/advisories/icsa-21-159-11
cvelogic Threat Intelligence