Crypto-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.
- Published
- Aug 7, 2017
- Updated
- Jun 16, 2026
- EPSS
- 81.8% · 100th percentile
- CWE
- CWE-287
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Action score
64
This week
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- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 25 / 30 · 81.8%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| ntp | ntp | cpe:2.3:a:ntp:ntp |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| 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 |
| netapp | clustered data ontap | cpe:2.3:o:netapp:clustered_data_ontap |
| netapp | data ontap | cpe:2.3:o:netapp:data_ontap |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux7.0
- debian debian linux8.0
- debian debian linux9.0
- netapp clustered data ontapall versions
- netapp data ontapall versions
- netapp oncommand balanceall versions
- netapp oncommand performance managerall versions
- netapp oncommand unified managerall versions
- ntp ntp4.3.0 and later · before 4.3.77
- ntp ntp4.2.6 and later · before 4.2.8
- ntp ntp4.2.5
- ntp ntp4.2.8
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 1:4.2.8p4+dfsg-1 | 1:4.2.8p4+dfsg-1 |
| Debian:6.0 | ntp | before 1:4.2.6.p2+dfsg-1+deb6u4 | 1:4.2.6.p2+dfsg-1+deb6u4 |
| Debian:7 | ntp | before 1:4.2.6.p5+dfsg-2+deb7u6 | 1:4.2.6.p5+dfsg-2+deb7u6 |
| Debian:8 | ntp | before 1:4.2.6.p5+dfsg-7+deb8u1 | 1:4.2.6.p5+dfsg-7+deb8u1 |
| SUSE:Linux Enterprise Desktop 11 SP4 | ntp | before 4.2.8p4-5.1 | 4.2.8p4-5.1 |
| SUSE:Linux Enterprise Desktop 12 | ntp | before 4.2.8p6-46.5.2 | 4.2.8p6-46.5.2 |
| SUSE:Linux Enterprise Desktop 12 | yast2-ntp-client | before 3.1.12.4-8.2 | 3.1.12.4-8.2 |
| SUSE:Linux Enterprise Server 11 SP2-LTSS | yast2-ntp-client | before 2.17.14.1-1.12.1 | 2.17.14.1-1.12.1 |
| SUSE:OpenStack Cloud 5 | ntp | before 4.2.8p6-41.1 | 4.2.8p6-41.1 |
Same product
ntp: all recordsOther highest-scoring records for the same primary product.
- 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, rel54Plan
- 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 amplificat49Plan
- CVE-2018-12327Stack-based buffer overflow in ntpq and ntpdc of NTP version 4.2.8p11 allows an attacker to achieve code execution or escalate to higher pri47Plan
- CVE-2016-7434The read_mru_list function in NTP before 4.2.8p9 allows remote attackers to cause a denial of service (crash) via a crafted mrulist query.46Plan
- CVE-2015-7853The 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 arbitra43Plan
- CVE-2015-7705The rate limiting feature in NTP 4.x before 4.2.8p4 and 4.3.x before 4.3.77 allows remote attackers to have unspecified impact via a large n43Plan
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 | 1:4.2.8p4+dfsg-1 · Debian:11 | Package registry (OSV) |
| suse:ntp | 4.2.8p4-5.1 · SUSE:Linux Enterprise Desktop 11 SP4 | Package registry (OSV) |
| suse:yast2-ntp-client | 3.1.12.4-8.2 · SUSE:Linux Enterprise Desktop 12 | Package registry (OSV) |
Exploit status
Weaponized
A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.
Evidence
- Metasploit module ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Metasploit module | auxiliary/scanner/ntp/ntp_nak_to_the_futureNTP "NAK to the Future"auxiliary | — |
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.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
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
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-287 · Improper AuthenticationCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
app.use("/admin", requireSession, adminRouter);
// Route added later skips the middlewareapp.post("/admin-api/config", updateConfig);Fixed
const admin = express.Router();admin.use(requireSession, requireRole("admin"));
admin.post("/config", updateConfig);app.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)
- Authentication AbuseCAPEC-114Medium
- Authentication BypassCAPEC-115Medium
- Identity SpoofingCAPEC-151likelihood: Medium · Medium
- Fake the Source of DataCAPEC-194Medium
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- Utilizing REST's Trust in the System Resource to Obtain Sensitive DataCAPEC-57likelihood: Medium · Very High
- Session HijackingCAPEC-593likelihood: High · Very High
- Token ImpersonationCAPEC-633Medium
ATT&CK techniques
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- support.ntp.org/bin/view/Main/NtpBug2941
- www.debian.org/security/2015/dsa-3388
- www.securityfocus.com/bid/77287
- www.securitytracker.com/id/1033951
- bugzilla.redhat.com/show_bug.cgi?id=1274265
- cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf
- h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05270839
- security.gentoo.org/glsa/201604-03
- security.gentoo.org/glsa/201607-15
- security.netapp.com/advisory/ntap-20171004-0001/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.