CVE-2023-4012Network attack vector

Unauthenticated service crash via missing NTS keys

Published Aug 7, 2023 · Updated Jun 22, 2026

Denial of service in NTPsec ntpd 1.2.2 allows remote attackers to crash the daemon via an NTS-enabled mode 3 request. The nts_unpack_cookie function passes a null cookie key into AES-SIV decryption when nts_nKeys is zero instead of rejecting the cookie. An unauthenticated network request reaches this path only when the server runs without NTS keys; the resulting segmentation fault stops time service until ntpd restarts.

CVSS severity7.5
High
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in NTPsec ntpd 1.2.2 allows remote attackers to crash the daemon via an NTS-enabled mode 3 request. The nts_unpack_cookie function passes a null cookie key into AES-SIV decryption when nts_nKeys is zero instead of rejecting the cookie. An unauthenticated network request reaches this path only when the server runs without NTS keys; the resulting segmentation fault stops time service until ntpd restarts.

The record

CVE
CVE-2023-4012
Published
Aug 7, 2023
Updated
Jun 22, 2026
Vendor
NTPsec
Product
NTPsec
Classifications
CWE-372, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 7, 2023CVE publishedPublication date reported by the CVE source.
  2. Jun 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NTPsec · NTPsecversion=1.2.2

Published CVSS scores

7.5GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-372Incomplete Internal State Distinction
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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