CVE-2015-7975
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 · uneditedThe nextvar function in NTP before 4.2.8p6 and 4.3.x before 4.3.90 does not properly validate the length of its input, which allows an attacker to cause a denial of service (application crash).
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 · moderate confidenceThe nextvar function in NTP versions prior to 4.2.8p6 and 4.3.x prior to 4.3.90 fails to properly validate input length, allowing a crafted packet to trigger a buffer handling error resulting in application crash and denial of service.
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<= 4.2.8= 4.3.0= 4.3.1= 4.3.2= 4.3.3= 4.3.4= 4.3.5= 4.3.6= 4.3.7= 4.3.8= 4.3.10= 4.3.11CVSS 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
- Local
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 NTP installation and versionRun `ntpdc --version` or `ntpd --version` to obtain the installed NTP daemon version. On Linux systems, also try `dpkg -l | grep ntp` or `rpm -q ntp` to check the package version.Affected if The version returned is any of the following: NTP 4.2.8 and prior, 4.3.0, 4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.3.5, 4.3.6, 4.3.7, 4.3.8, 4.3.10, or 4.3.11.
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Verify NTP server mode is enabledCheck the NTP configuration file (typically /etc/ntp.conf) or run `ntpq -p` to confirm the daemon is operating in server or peer mode and accepting remote queries.Affected if The NTP daemon is running as a server (listening on UDP port 123) or is configured to accept mode 6 or mode 7 requests from the network.
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Confirm nextvar function exposureUse `ntpdc -c sysinfo` or `ntpdc -c peers` to send mode 6 control queries to the local NTP daemon. The vulnerable nextvar function processes variable-length requests in these control packets.Affected if The NTP daemon responds to control queries without dropping packets, indicating the nextvar function is reachable.
If the installed NTP version matches any affected version (4.2.8 and below, or 4.3.0-4.3.11 excluding 4.3.9) AND the daemon is running as a network-accessible server, the environment is vulnerable to CVE-2015-7975.
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 NTP to version 4.2.8p6 or later, or 4.3.90 or later in the 4.3.x branch, to obtain the patched nextvar function with proper input length validation.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-7975 — 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 sources- support.ntp.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- tools.cisco.com
- www.securityfocus.com
- www.securitytracker.com
- www.ubuntu.com
- bto.bluecoat.com
- security.gentoo.org
- www.kb.cert.org
- h20566.www2.hpe.com
- h20566.www2.hpe.com
- security.FreeBSD.org
- security.netapp.com
- nvd.nist.gov
Practitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2015-7975 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
- No weaponised exploit code, or anything meant to cause harm
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