# CVE-2026-93007: Dnsmasq: dnsmasq: tcp/53 child-slot exhaustion starves dnssec validation

Status: published. Published: 2026-10-29. Updated: 2026-11-06.

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.

## Remediation

- workaround: The following measures reduce risk:

1. Increase the TCP connection limit with --max-tcp-connections=<N> to raise the number of connections an attacker must hold.
2. Limit per-source TCP connections to port 53 with firewall rules, for example iptables connlimit on tcp/53.
3. Restrict which hosts can reach TCP port 53 if TCP DNS is not required from untrusted networks. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Ceph Storage 9 (rhceph/alloy-rhel10): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (dnsmasq): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (dnsmasq): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (dnsmasq): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (dnsmasq): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (dnsmasq): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift4/ose-baremetal-runtimecfg-rhel8): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift4/ose-baremetal-runtimecfg-rhel9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 5 (openshift5/ose-baremetal-runtimecfg-rhel9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 5 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenStack Platform 13 (Queens) (dnsmasq): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenStack Platform 18.0 (rhoso-operators/infra-rhel9-operator): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 5.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.43% as of 2026-11-05; percentile 37.08%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-400

## Exploit evidence

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

## References

- https://access.redhat.com/security/cve/CVE-2026-93007 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2536076 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-93007; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-93007; retrieved 2026-11-06; source updated Not reported

Revision: 58eab4886207adfb962114d50a79cfd8fcbb502655f88fee60814c985d873e21

Canonical: https://y2.dev/cve/CVE-2026-93007

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