The symmetric-key feature in the receive function in ntp_proto.c in ntpd in NTP 3.x and 4.x before 4.2.8p2 performs state-variable updates u
The symmetric-key feature in the receive function in ntp_proto.c in ntpd in NTP 3.x and 4.x before 4.2.8p2 performs state-variable updates upon receiving certain invalid packets, which makes it easier for man-in-the-middle attackers to cause a denial of service (synchronization loss) by spoofing the source IP address of a peer.
- Published
- Apr 8, 2015
- Updated
- Jun 16, 2026
- EPSS
- 0.9% · 59th percentile
- CWE
- CWE-17
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Report tools
Action score
17
Monitor
Low priority for now.
- CVSS
- 17 / 40 · 4.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.9%
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; 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 helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| ntp | ntp | cpe:2.3:a:ntp:ntp |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- ntp ntpup to 4.2.7p444 inclusive
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 1:4.2.6.p5+dfsg-6 | 1:4.2.6.p5+dfsg-6 |
| Debian:6.0 | ntp | before 1:4.2.6.p2+dfsg-1+deb6u3 | 1:4.2.6.p2+dfsg-1+deb6u3 |
| Debian:7 | ntp | before 1:4.2.6.p5+dfsg-2+deb7u4 | 1:4.2.6.p5+dfsg-2+deb7u4 |
| openSUSE:Tumbleweed | ntp | before 4.2.8p9-1.1 | 4.2.8p9-1.1 |
| Red Hat:enterprise_linux:6::client | ntp | before 0:4.2.6p5-5.el6 | 0:4.2.6p5-5.el6 |
| Red Hat:enterprise_linux:6::client | ntp-debuginfo | before 0:4.2.6p5-5.el6 | 0:4.2.6p5-5.el6 |
| Red Hat:enterprise_linux:6::client | ntp-doc | before 0:4.2.6p5-5.el6 | 0:4.2.6p5-5.el6 |
| Red Hat:enterprise_linux:6::client | ntp-perl | before 0:4.2.6p5-5.el6 | 0:4.2.6p5-5.el6 |
| Red Hat:enterprise_linux:6::client | ntpdate | before 0:4.2.6p5-5.el6 | 0:4.2.6p5-5.el6 |
| Red Hat:enterprise_linux:7::client | ntp | before 0:4.2.6p5-22.el7 | 0:4.2.6p5-22.el7 |
| Red Hat:enterprise_linux:7::client | ntp-debuginfo | before 0:4.2.6p5-22.el7 | 0:4.2.6p5-22.el7 |
| Red Hat:enterprise_linux:7::client | ntp-doc | before 0:4.2.6p5-22.el7 | 0:4.2.6p5-22.el7 |
| Red Hat:enterprise_linux:7::client | ntp-perl | before 0:4.2.6p5-22.el7 | 0:4.2.6p5-22.el7 |
| Red Hat:enterprise_linux:7::client | ntpdate | before 0:4.2.6p5-22.el7 | 0:4.2.6p5-22.el7 |
| Red Hat:enterprise_linux:7::client | sntp | before 0:4.2.6p5-22.el7 | 0:4.2.6p5-22.el7 |
| SUSE:Linux Enterprise Desktop 12 | ntp | before 4.2.6p5-44.1 | 4.2.6p5-44.1 |
Same product
ntp: all recordsOther 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, 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
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 | 1:4.2.6.p5+dfsg-6 · Debian:11 | Package registry (OSV) |
| opensuse:ntp | 4.2.8p9-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:ntp | 0:4.2.6p5-5.el6 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:ntp-debuginfo | 0:4.2.6p5-5.el6 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:ntp-doc | 0:4.2.6p5-5.el6 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:ntp-perl | 0:4.2.6p5-5.el6 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:ntpdate | 0:4.2.6p5-5.el6 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:sntp | 0:4.2.6p5-22.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| suse:ntp | 4.2.6p5-44.1 · SUSE:Linux Enterprise Desktop 12 | 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.
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
If successful
- Confidentiality
- none
- Integrity
- P · data or configuration can be modified
- Availability
- P · the service can be disrupted
- Attack complexity
- M
- Confidentiality impact
- None
- Integrity impact
- P
- Availability impact
- P
Weakness class (CWE)
CWE-17 · DEPRECATED: CodeCVSS vector
AV:A/AC:M/Au:N/C:N/I:P/A:P
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- bugs.ntp.org/show_bug.cgi?id=2781
- listengine.tuxfamily.org/chrony.tuxfamily.org/chrony-announce/2015/04/msg00002.html
- lists.apple.com/archives/security-announce/2015/Jun/msg00002.html
- lists.fedoraproject.org/pipermail/package-announce/2015-April/155863.html
- lists.fedoraproject.org/pipermail/package-announce/2015-April/155864.html
- lists.opensuse.org/opensuse-updates/2015-04/msg00052.html
- marc.info/?l=bugtraq&m=143213867103400&w=2
- marc.info/?l=bugtraq&m=145750740530849&w=2
- rhn.redhat.com/errata/RHSA-2015-1459.html
- support.apple.com/kb/HT204942
- support.ntp.org/bin/view/Main/SecurityNotice#Recent_Vulnerabilities
- tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20150408-ntpd
- tools.cisco.com/security/center/viewAlert.x?alertId=38275
- www.debian.org/security/2015/dsa-3222
- www.debian.org/security/2015/dsa-3223
- www.kb.cert.org/vuls/id/374268
- www.mandriva.com/security/advisories?name=MDVSA-2015:202
- www.oracle.com/technetwork/topics/security/bulletinapr2015-2511959.html
- www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
- www.securityfocus.com/bid/73950
Vendor advisories and official records. Exploit/PoC links are deliberately left out.