A flaw was found in dnsmasq. The DHCPv6 client hostname parser can read one byte past the end of a crafted FQDN option because it checks the next label length before confirming the pointer is still inside the option. An attacker on the local network can trigger this with a single DHCPv6 packet. The extra byte is not returned to the client or logged, and no crash has been demonstrated.
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

The following measures reduce risk: 1. If DHCPv6 is not required, do not configure any IPv6 dhcp-range. 2. Compile without DHCPv6 using COPTS=-DNO_DHCP6 if IPv6 DHCP is not needed. 3. Restrict dnsmasq to trusted interfaces with --interface=<iface>.

History

Thu, 29 Oct 2026 13:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in dnsmasq. The DHCPv6 client hostname parser can read one byte past the end of a crafted FQDN option because it checks the next label length before confirming the pointer is still inside the option. An attacker on the local network can trigger this with a single DHCPv6 packet. The extra byte is not returned to the client or logged, and no crash has been demonstrated.
Title Dnsmasq: dnsmasq: heap out-of-bounds read in dhcpv6 option 39 fqdn decoder
First Time appeared Redhat
Redhat ceph Storage
Redhat enterprise Linux
Redhat openshift
Redhat openstack
Weaknesses CWE-125
CPEs cpe:/a:redhat:ceph_storage:9
cpe:/a:redhat:openshift:4
cpe:/a:redhat:openstack:13
cpe:/a:redhat:openstack:18.0
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat ceph Storage
Redhat enterprise Linux
Redhat openshift
Redhat openstack
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-10-29T13:13:34.504Z

Reserved: 2026-09-17T14:35:34.562Z

Link: CVE-2026-93009

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-29T14:18:00.367

Modified: 2026-10-29T14:18:00.480

Link: CVE-2026-93009

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-29T15:45:06Z

Weaknesses