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DhcpApplication · Isc

CVE-2011-0413

HIGH · 7.8 CVSS v2.0 Published 2011-01-31
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
87/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
The DHCPv6 server in ISC DHCP 4.0.x and 4.1.x before 4.1.2-P1, 4.0-ESV and 4.1-ESV before 4.1-ESV-R1, and 4.2.x before 4.2.1b1 allows remote attackers to cause a denial of service (assertion failure and daemon crash) by sending a message over IPv6 for a declined and abandoned address.

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 confidence

The ISC DHCPv6 server versions 4.0.x, 4.1.x before 4.1.2-P1, 4.0-ESV and 4.1-ESV before 4.1-ESV-R1, and 4.2.x before 4.2.1b1 contain an assertion failure vulnerability when processing DHCPv6 messages for declined and abandoned IPv6 addresses. Remote attackers can send specially crafted IPv6 messages causing the daemon to crash via assertion failure, resulting in denial of service.

MitigationUpdate ISC DHCP to version 4.1.2-P1, 4.1-ESV-R1, 4.2.1b1 or later to patch the assertion vulnerability. If immediate patching is not possible, restrict IPv6 network access to the DHCPv6 server to limit exposure.

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
DhcpApplication
Affected:= 4.0= 4.0.0= 4.0.1= 4.0.2= 4.0.3= 4.1.0= 4.1.1= 4.1.2= 4.0-esv= 4.1-esv= 4.2.0

CVSS 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
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete

AV:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify ISC DHCP server installation and version
    Run 'dhcpd -v' or 'dhcpd6 -v' to display the DHCP daemon version. On Linux, also check '/usr/sbin/dhcpd' version via 'dhcpd --version'. Package managers can be used: 'rpm -q dhcp' (RHEL/CentOS), 'dpkg -l isc-dhcp-server' (Debian/Ubuntu), or 'yum list dhcp' (Fedora).
    Affected if The installed version is 4.0.x, 4.1.x before 4.1.2-P1, 4.0-ESV, 4.1-ESV before 4.1-ESV-R1, or 4.2.x before 4.2.1b1. Specifically, versions 4.0, 4.0.0, 4.0.1, 4.0.2, 4.0.3, 4.1.0, 4.1.1, 4.1.2, 4.0-esv, 4.1-esv, or 4.2.0 are affected.
  2. Confirm DHCPv6 server process is running
    Check for running dhcpd process with IPv6 capability. Run 'ps aux | grep dhcpd' and look for dhcpd process. Use 'netstat -uanp | grep 547' or 'ss -uanp | grep 547' to check if the DHCPv6 service is listening on UDP port 547 (DHCPv6 server port).
    Affected if The DHCPv6 server daemon (dhcpd) is actively running and listening on IPv6.
  3. Verify IPv6 network binding configuration
    Inspect the DHCP server configuration file typically located at '/etc/dhcp/dhcpd.conf' or '/etc/dhcpd.conf'. Look for 'dhcpd6.conf' if separate IPv6 configuration exists. Check for 'authoritative;' directive and any 'interface' or 'bind-interface' statements indicating IPv6 binding.
    Affected if The DHCP server is configured to bind to IPv6 interfaces or the configuration file explicitly enables DHCPv6 service.
  4. Check IPv6 network exposure
    Review firewall rules and network access controls. Run 'iptables -L -n' for IPv4 and 'ip6tables -L -n' for IPv6 to determine if the DHCPv6 port 547/UDP is accessible. Verify if the server has a public or otherwise accessible IPv6 address.
    Affected if The DHCPv6 server (port 547/UDP) is reachable from untrusted IPv6 networks, increasing exposure to remote attack.

A user is affected if they are running a vulnerable ISC DHCP version (4.0.x, 4.1.x before 4.1.2-P1, 4.0-ESV/4.1-ESV before patches, or 4.2.x before 4.2.1b1) with the DHCPv6 server enabled and accessible over IPv6 networks.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update ISC DHCP to version 4.1.2-P1, 4.1-ESV-R1, 4.2.1b1 or later to patch the assertion vulnerability. If immediate patching is not possible, restrict IPv6 network access to the DHCPv6 server to limit exposure.

Fix this in Dhcp Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,210
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2011-0413 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data