CVE-2011-4868
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 logging functionality in dhcpd in ISC DHCP before 4.2.3-P2, when using Dynamic DNS (DDNS) and issuing IPv6 addresses, does not properly handle the DHCPv6 lease structure, which allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via crafted packets related to a lease-status update.
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 logging functionality in dhcpd (ISC DHCP before 4.2.3-P2) fails to properly handle the DHCPv6 lease structure when using Dynamic DNS (DDNS) with IPv6 addresses. This improper handling leads to a NULL pointer dereference when processing crafted packets related to lease-status updates, causing the daemon to crash.
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<= 4.2.3= 3.0= 3.0.1= 3.0.2= 3.0.3= 3.0.4= 3.0.5= 3.0.6= 3.1.0= 4.0.0= 4.1.0= 4.2.0CVSS 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
- Adjacent
- Complexity
- Low
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:A/AC:L/Au:N/C:N/I:N/A:C
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 ISC DHCP versionRun 'dhcpd -v' or 'dhcpd6 -v' to display the installed version. On Linux, also check '/usr/sbin/dhcpd -v' or check RPM/DEB package version with 'rpm -q dhcp' or 'dpkg -l isc-dhcp-server'.Affected if The version is 4.2.3 or earlier, or specifically 3.0.x, 3.1.0, 4.0.0, 4.1.0, or 4.2.0 as listed in affected versions.
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Verify DDNS is enabledInspect the dhcpd.conf file (typically at '/etc/dhcpd.conf' or '/etc/dhcp/dhcpd.conf') for 'ddns-update-style' configuration directive. Also look for 'ddns-domainname' and 'ddns-rev-domainname' statements.Affected if DDNS update style is set to 'interim', 'standard', or any non-'none' value, indicating Dynamic DNS updates are enabled.
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Confirm DHCPv6 is in useCheck for dhcpd6 process running ('ps aux | grep dhcpd6') or look for dhcpd6 configuration file ('/etc/dhcpd6.conf' or '/etc/dhcp/dhcpd6.conf'). Also check if IPv6 addresses are assigned via DHCP.Affected if DHCPv6 daemon (dhcpd6) is running or configured to run, or the system uses DHCP for IPv6 address allocation.
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Check for lease file handlingExamine the dhcpd.leases or dhcpd6.leases file (typically in '/var/lib/dhcpd/' or '/var/lib/dhcp/') and confirm DDNS-related lease updates are being logged or processed.Affected if Lease files exist and DDNS is enabled, indicating the vulnerable code path for processing lease-status updates with IPv6 addresses is active.
A system is affected if it runs an ISC DHCP version <= 4.2.3 (or one of the specifically listed affected versions) with DDNS enabled and DHCPv6 configured, allowing the NULL pointer dereference when processing crafted lease-status packets.
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 ISC DHCP 4.2.3-P2 or later. If immediate patching is not possible, consider disabling DDNS if not required, and implement network segmentation to limit exposure to untrusted networks.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-4868 — 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-2011-4868 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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- Version or environment caveats, and links to real fixes
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