Dnsmasq TCP DNS child-slot exhaustion starves DNSSEC validation
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Deferred Red Hat: fix deferred
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-400.
Summary
Dnsmasq in Red Hat Enterprise Linux 6 and other Red Hat products is affected. A flaw (CWE-400) lets the TCP DNS service, which uses a small fixed pool of child processes and sets no receive timeout on client connections, be exhausted. A remote unauthenticated attacker can open idle TCP connections to port 53 and occupy the whole pool, which blocks new TCP DNS connections and DNSSEC validation that needs TCP fallback. UDP DNS resolution continues, and occupied slots are released after a fixed lifetime.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
A flaw was found in dnsmasq. The TCP DNS service uses a small fixed pool of child processes and does not set a receive timeout on client connections. A remote attacker can open idle TCP connections to port 53 and occupy the entire pool, preventing new TCP DNS connections and DNSSEC validation that requires TCP fallback. UDP DNS resolution continues, and occupied slots are released after a fixed lifetime.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Red Hat | Red Hat Ceph Storage 9 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 10 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 6 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 8 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenShift Container Platform 5 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenShift Container Platform 5 | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenStack Platform 13 (Queens) | — | — | No fix listed | CNA |
| Red Hat | Red Hat OpenStack Platform 18.0 | — | — | No fix listed | CNA |
- Red Hat Ceph Storage 9 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 10 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 6 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenShift Container Platform 5 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenShift Container Platform 5 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenStack Platform 13 (Queens) VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat OpenStack Platform 18.0 VendorRed Hat Affected — Fixed in — No fix listed CNA
CPE names CNA · 10
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:/a:redhat:ceph_storage:9 | 9 | — | Red Hat |
| cpe:/a:redhat:enterprise_linux:10 | 10 | — | Red Hat |
| cpe:/o:redhat:rhel_els:6 | 6 | — | Red Hat |
| cpe:/o:redhat:rhel_els:7 | 7 | — | Red Hat |
| cpe:/a:redhat:enterprise_linux:8 | 8 | — | Red Hat |
| cpe:/a:redhat:enterprise_linux:9 | 9 | — | Red Hat |
| cpe:/a:redhat:openshift:4 | 4 | — | Red Hat |
| cpe:/a:redhat:openshift:5 | 5 | — | Red Hat |
| cpe:/a:redhat:openstack:13 | 13 | — | Red Hat |
| cpe:/a:redhat:openstack:18.0 | 18.0 | — | Red Hat |
- cpe:/a:redhat:ceph_storage:9 Versions 9 — ·Red Hat
- cpe:/a:redhat:enterprise_linux:10 Versions 10 — ·Red Hat
- cpe:/o:redhat:rhel_els:6 Versions 6 — ·Red Hat
- cpe:/o:redhat:rhel_els:7 Versions 7 — ·Red Hat
- cpe:/a:redhat:enterprise_linux:8 Versions 8 — ·Red Hat
- cpe:/a:redhat:enterprise_linux:9 Versions 9 — ·Red Hat
- cpe:/a:redhat:openshift:4 Versions 4 — ·Red Hat
- cpe:/a:redhat:openshift:5 Versions 5 — ·Red Hat
- cpe:/a:redhat:openstack:13 Versions 13 — ·Red Hat
- cpe:/a:redhat:openstack:18.0 Versions 18.0 — ·Red Hat
Remediation
The sources list no fixed version for dnsmasq. Red Hat's plan for its affected products is none available.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Ceph Storage 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 13 (Queens) | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 18.0 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-29 Threatist record created from CVE-2026-93007
- 2026-10-29 Alias added: GHSA-2frf-fr59-fcjq
- 2026-10-29 CISA SSVC decision points changed
- 2026-10-29 Affected versions changed · Red Hat
- 2026-10-29 CVSS score added · Red Hat
- 2026-10-30 Affected versions changed · CNA
- 2026-10-30 Affected versions changed · Red Hat
References
More Red Hat vulnerabilities
- TI-2019-15875 Protection mechanism failure in Jenkins Pipeline: Groovy Plugin KEVCVSS 3.1CRITICAL 9.9
- TI-2019-15874 Protection mechanism failure in Jenkins Script Security Plugin KEVCVSS 3.1CRITICAL 9.9
- TI-2019-08259 Underflow in PHP-FPM can lead to RCE KEVCVSS 3.1CRITICAL 9.8
- TI-2019-05363 Code injection in Elastic Kibana KEVCVSS 3.1CRITICAL 10.0
- TI-2019-03949 Out-of-bounds write in ESXi and Horizon DaaS KEVCVSS 3.1CRITICAL 9.8
- TI-2018-16080 A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153… KEVCVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-93007 · CVE Program
- CVE-2026-93007 · NVD
- FIRST EPSS
- GHSA-2frf-fr59-fcjq · GitHub Advisory Database · CC BY 4.0
- CVE-2026-93007 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences