Dnsmasq: dnsmasq: denial of service due to out-of-bounds write in dhcp bootreply processing

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Summary

CVECVE-2026-6507
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-17 13:16:14 UTC
Updated2026-04-17 15:07:18 UTC
DescriptionA 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).

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.000330000 probability, percentile 0.095340000 (date 2026-04-21)

Problem Types: CWE-787 | CWE-787 Out-of-bounds Write

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Enterprise Linux 10 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 9 Not specified Not specified
CNA Red Hat Red Hat OpenShift Container Platform 4 Not specified Not specified

References

ReferenceSourceLinkTags
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
access.redhat.com/security/cve/CVE-2026-6507 [email protected] access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
CNA2026-04-17T00:00:00.000ZReported to Red Hat.
CNA2026-04-17T11:37:00.000ZMade public.

Workarounds

CNA: To mitigate this issue, ensure that the `dnsmasq` service is not configured with the `--dhcp-split-relay` option. If this option is currently in use, remove it from the `dnsmasq` configuration. After modifying the configuration, the `dnsmasq` service must be restarted for the changes to take effect. This may temporarily interrupt DHCP and DNS services provided by `dnsmasq`.

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