CVE-2026-6507

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

publishedCWE-787

A 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 severity7.5 highCVSS 3.1 · CNA: redhat

Published2026-04-17Source updated 2026-11-05

Collected2026-11-052 attributed sources

Fixes and workarounds

Workaround

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`.

Source: CNA: redhat

Affected products and versions

Affected products, source version ranges and reporting authorities
Product	Versions	Authority
`dnsmasq` https://thekelleys.org.uk/git/dnsmasq.git	≥ 2.92; < 2.93 (affected, semver) Other versions: unaffected	CNA: redhat
Red Hat Enterprise Linux 10 Red Hat `dnsmasq` https://access.redhat.com/downloads/content/package-browser/	Range not reported Other versions: unaffected	CNA: redhat
Red Hat Enterprise Linux 6 Red Hat `dnsmasq` https://access.redhat.com/downloads/content/package-browser/	Range not reported Other versions: unaffected	CNA: redhat
Red Hat Enterprise Linux 7 Red Hat `dnsmasq` https://access.redhat.com/downloads/content/package-browser/	Range not reported Other versions: unaffected	CNA: redhat
Red Hat Enterprise Linux 8 Red Hat `dnsmasq` https://access.redhat.com/downloads/content/package-browser/	Range not reported Other versions: unaffected	CNA: redhat
Red Hat Enterprise Linux 9 Red Hat `dnsmasq` https://access.redhat.com/downloads/content/package-browser/	Range not reported Other versions: unaffected	CNA: redhat
Red Hat OpenShift Container Platform 4 Red Hat `openshift/ose-rhel-coreos-8` https://access.redhat.com/downloads/content/package-browser/	Range not reported Other versions: unaffected	CNA: redhat
Red Hat OpenShift Container Platform 4 Red Hat `openshift/ose-rhel-coreos-9` https://access.redhat.com/downloads/content/package-browser/	Range not reported Other versions: unaffected	CNA: redhat

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

CVSS assessments

CVSS scores, vectors and reporting authorities
Version / score	Vector	Authority
3.1 / 7.5 high	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`	CNA: redhat

Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

References

https://access.redhat.com/security/cve/CVE-2026-6507CNA: redhat · vdb-entry, x_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2459181CNA: redhat · issue-tracking, x_refsource_REDHAT

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