Vulnerability · Published Oct 29, 2026 · Assigned by redhat
CVE-2026-93009Dnsmasq: dnsmasq: heap out-of-bounds read in dhcpv6 option 39 fqdn decoder
Medium 4.3
In plain English
A medium-severity out-of-bounds read in Red Hat Ceph Storage 9 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities).
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | dnsmasq | no fix listed | DEBIAN-CVE-2026-93009 |
| Debian:13 | dnsmasq | no fix listed | DEBIAN-CVE-2026-93009 |
| Debian:14 | dnsmasq | no fix listed | DEBIAN-CVE-2026-93009 |
| Ubuntu:22.04:LTS | dnsmasq | no fix listed | UBUNTU-CVE-2026-93009 |
| Ubuntu:24.04:LTS | dnsmasq | no fix listed | UBUNTU-CVE-2026-93009 |
| Ubuntu:26.04:LTS | dnsmasq | no fix listed | UBUNTU-CVE-2026-93009 |
| Ubuntu:26.10 | dnsmasq | no fix listed | UBUNTU-CVE-2026-93009 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Ceph Storage 9 | see references |
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 7 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 5 | see references |
| Red Hat | Red Hat OpenShift Container Platform 5 | see references |
| Red Hat | Red Hat OpenStack Platform 13 (Queens) | see references |
| Red Hat | Red Hat OpenStack Platform 18.0 | see references |
Weakness: CWE-125 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
References
- https://access.redhat.com/security/cve/CVE-2026-93009 vdb-entry, x_refsource_REDHAT
- RHBZ#2536083 issue-tracking, x_refsource_REDHAT