CVE-2026-6507
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 · uneditedA flaw was found in dnsmasq. A remote attacker could exploit an out-of-bounds write vulnerability by sending a specially crafted BOOTREPLY (Bootstrap Protocol Reply) packet to a dnsmasq server configured with the `--dhcp-split-relay` option. This can lead to memory corruption, causing the dnsmasq daemon to crash and resulting in a denial of service (DoS).
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 confidenceAn out-of-bounds write vulnerability exists in dnsmasq when configured with the `--dhcp-split-relay` option. A remote attacker can send a specially crafted BOOTREPLY (BOOTP) packet to trigger a buffer overflow, leading to memory corruption and daemon crash resulting in denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/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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Verify dnsmasq is installedRun 'dnsmasq --version' or check package manager (e.g., 'dpkg -l | grep dnsmasq', 'rpm -qa | grep dnsmasq')Affected if dnsmasq is present on the system
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Identify the installed dnsmasq versionRun 'dnsmasq --version' to get the exact version number, then compare against any affected version ranges if documentedAffected if the installed version falls within an affected version range (if known)
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Check if --dhcp-split-relay option is configuredReview all dnsmasq configuration files (/etc/dnsmasq.conf, /etc/dnsmasq.d/*, and command-line arguments) for the presence of 'dhcp-split-relay' or '--dhcp-split-relay'Affected if the --dhcp-split-relay option is enabled in any dnsmasq configuration
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Inspect running dnsmasq process argumentsRun 'ps aux | grep dnsmasq' to see the active command-line arguments of the running dnsmasq processAffected if the running dnsmasq process includes --dhcp-split-relay in its arguments
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Check for dnsmasq crash indicatorsReview system logs (/var/log/syslog, /var/log/messages, journalctl -u dnsmasq) for recent dnsmasq crash entries or denial of service eventsAffected if dnsmasq has recently crashed or terminated unexpectedly
The environment is affected if dnsmasq is running with the --dhcp-split-relay option enabled and the installed version is within the affected range, regardless of whether crashes have occurred.
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 dataIf the `--dhcp-split-relay` option is not required, disable or remove it from the dnsmasq configuration. If required, restrict network access to the DHCP service to trusted sources only and monitor for attempts to exploit this vulnerability.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-6507 — 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-2026-6507 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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