CVE-2023-26554Public exploitNetwork attack vector

ntpq interruption via out-of-bounds terminator write

Published Apr 11, 2023 · Updated Feb 11, 2025

Out-of-bounds write in mstolfp in NTP 4.2.8p15 allows remote attackers to interrupt ntpq through a malicious server response. The libntp/mstolfp.c parser appends a null terminator beyond its destination buffer while converting an attacker-controlled fixed-point value. Only a command-line ntpq user who queries an attacker-controlled server reaches the flaw; ntpd is not affected.

CVSS severity5.6
Medium
EPSS probability0.65%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in mstolfp in NTP 4.2.8p15 allows remote attackers to interrupt ntpq through a malicious server response. The libntp/mstolfp.c parser appends a null terminator beyond its destination buffer while converting an attacker-controlled fixed-point value. Only a command-line ntpq user who queries an attacker-controlled server reaches the flaw; ntpd is not affected.

The record

CVE
CVE-2023-26554
Published
Apr 11, 2023
Updated
Feb 11, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 11, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 11, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3IBM X-ForceCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
4.4SUSECVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
5.6NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
5.6CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

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 exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

Public exploit references

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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