NVD / CVE Program· CNA mitre

CVE-2016-4953: ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (ephemeral-association demobilization) by sending a…

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 35/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 17.2% (FIRST EPSS); higher than 97.1% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: ntp (Debian:11) 1:4.2.8p8+dfsg-1; ntp (SUSE:Linux Enterprise Desktop 12) 4.2.8p8-46.8.1; ntp (SUSE:Linux Enterprise Desktop 12 SP1) 4.2.8p8-14.1.

Low priority for now. Upgrade to ntp (Debian:11) 1:4.2.8p8+dfsg-1; ntp (SUSE:Linux Enterprise Desktop 12) 4.2.8p8-46.8.1; ntp (SUSE:Linux Enterprise Desktop 12 SP1) 4.2.8p8-14.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (ephemeral-association demobilization) by sending a spoofed crypto-NAK packet with incorrect authentication data at a certain time.

Published: Jul 4, 2016
Updated: Jun 16, 2026
EPSS: 17.2% · 97th percentile
CWE: CWE-287

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 5 / 30 · 17.2%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
ntp	ntp	cpe:2.3:a:ntp:ntp
oracle	solaris	cpe:2.3:o:oracle:solaris
suse	manager	cpe:2.3:a:suse:manager
suse	manager proxy	cpe:2.3:a:suse:manager_proxy
suse	openstack cloud	cpe:2.3:a:suse:openstack_cloud
opensuse	leap	cpe:2.3:o:opensuse:leap
opensuse	opensuse	cpe:2.3:o:opensuse:opensuse
suse	linux enterprise desktop	cpe:2.3:o:suse:linux_enterprise_desktop
suse	linux enterprise server	cpe:2.3:o:suse:linux_enterprise_server
siemens	simatic net cp 443-1 opc ua firmware	cpe:2.3:o:siemens:simatic_net_cp_443-1_opc_ua_firmware
siemens	simatic net cp 443-1 opc ua	cpe:2.3:h:siemens:simatic_net_cp_443-1_opc_ua
siemens	tim 4r-ie firmware	cpe:2.3:o:siemens:tim_4r-ie_firmware

and 3 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

ntp ntp4.2.0 and later · before 4.2.8
ntp ntp4.3.0 and later · before 4.3.93
ntp ntp4.2.8
opensuse leap42.1
opensuse opensuse13.2
oracle solaris10
oracle solaris11.3
siemens simatic net cp 443-1 opc ua firmwareall versions

+8 more rows

siemens tim 4r-ie dnp3 firmwareall versions
siemens tim 4r-ie firmwareall versions
suse linux enterprise desktop12
suse linux enterprise server11
suse linux enterprise server12
suse manager2.1
suse manager proxy2.1
suse openstack cloud5

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:11	ntp	before 1:4.2.8p8+dfsg-1	1:4.2.8p8+dfsg-1
SUSE:Linux Enterprise Desktop 12	ntp	before 4.2.8p8-46.8.1	4.2.8p8-46.8.1
SUSE:Linux Enterprise Desktop 12 SP1	ntp	before 4.2.8p8-14.1	4.2.8p8-14.1
SUSE:OpenStack Cloud 5	ntp	before 4.2.8p8-47.3	4.2.8p8-47.3

Same product

ntp: all records

Other highest-scoring records for the same primary product.

CVE-2015-7871Crypto-NAK packets in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to bypass authentication.
64This week
CVE-2014-9295Multiple stack-based buffer overflows in ntpd in NTP before 4.2.8 allow remote attackers to execute arbitrary code via a crafted packet…
54Plan
CVE-2013-5211The monlist feature in ntp_request.c in ntpd in NTP before 4.2.7p26 allows remote attackers to cause a denial of service (traffic…
49Plan

Published before and after this one in the same product

← EarlierCVE-2014-9751Oct 5, 2015 · The read_network_packet function in ntp_io.c in ntpd in NTP 4.x before 4.2.8p1 on Linux and OS X does not properly determine whether a…
28Monitor
← EarlierCVE-2015-7974Jan 26, 2016 · NTP 4.x before 4.2.8p6 and 4.3.x before 4.3.90 do not verify peer associations of symmetric keys when authenticating packets, which might…
32Monitor
Later →CVE-2016-4954Jul 4, 2016 · The process_packet function in ntp_proto.c in ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service…
34Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
debian:ntp	1:4.2.8p8+dfsg-1 · Debian:11	Package registry (OSV)
suse:ntp	4.2.8p8-14.1 · SUSE:Linux Enterprise Desktop 12 SP1	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: High

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1app.use("/admin", requireSession, adminRouter);
2

3// Route added later skips the middleware
4app.post("/admin-api/config", updateConfig);

Fixed

1const admin = express.Router();
2admin.use(requireSession, requireRole("admin"));
3

4admin.post("/config", updateConfig);
5app.use("/admin", admin);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Change log (1)

Fix✗ → ✓Sep 28, 2026, 10:48 PM UTC

For records you follow, these changes also arrive as notifications. →

References

bugs.ntp.org/3045

Show all references (19 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records