CVE-2023-26554
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedmstolfp in libntp/mstolfp.c in NTP 4.2.8p15 has an out-of-bounds write when adding a '\0' character. An adversary may be able to attack a client ntpq process, but cannot attack ntpd.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe mstolfp function in libntp/mstolfp.c (NTP 4.2.8p15) contains an out-of-bounds write vulnerability when adding a null terminator character. This buffer overflow occurs during string-to-float conversion and specifically affects the ntpq client utility, but cannot be exploited against the ntpd daemon.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 4.2.8CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed NTP client versionRun 'ntpq --version' or 'ntpq -V' to see the installed version of the ntpq utility. Alternatively, check your package manager (dpkg -l ntp, rpm -q ntp, or similar) for the installed NTP package version.Affected if The version is 4.2.8p15 or earlier (4.2.8, 4.2.8p1 through 4.2.8p15). Versions prior to 4.2.8 are not affected.
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Confirm ntpq utility is presentVerify the ntpq binary exists on the system by running 'which ntpq' or 'ls -l /usr/bin/ntpq'. This utility is included in the ntp package.Affected if The ntpq utility is installed. This is the specific component affected by CVE-2023-26554.
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Check if ntpq has network access or is exposed to untrusted inputReview any scripts, cron jobs, or automated processes that invoke ntpq and connect to remote NTP servers. Examine file permissions on ntpq (ls -l /usr/bin/ntpq) to see if untrusted local users can execute it.Affected if ntpq is used to query untrusted NTP servers, or untrusted users can invoke ntpq with controlled input.
You are affected if you are running NTP version 4.2.8p15 or earlier AND have the ntpq utility in use with exposure to untrusted input.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade to NTP version 4.2.8p16 or later where the vulnerability has been patched. If immediate patching is not possible, restrict network access to untrusted NTP servers and limit exposure of ntpq to untrusted input.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-26554 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-26554 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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