---
id: CVE-2026-93007
title: 'Dnsmasq: dnsmasq: tcp/53 child-slot exhaustion starves dnssec validation'
summary: >-
  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, …
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cvssSource: cna
cwe:
  - CWE-400
vendor: Red Hat
product: rhceph/alloy-rhel10
affected:
  - rhceph/alloy-rhel10 (all versions)
  - dnsmasq (all versions)
  - dnsmasq (all versions)
  - dnsmasq (all versions)
  - dnsmasq (all versions)
  - dnsmasq (all versions)
  - openshift4/ose-baremetal-runtimecfg-rhel8 (all versions)
  - openshift4/ose-baremetal-runtimecfg-rhel9 (all versions)
  - openshift/ose-rhel-coreos-8 (all versions)
  - openshift/ose-rhel-coreos-9 (all versions)
  - openshift5/ose-baremetal-runtimecfg-rhel9 (all versions)
  - openshift/ose-rhel-coreos-9 (all versions)
  - dnsmasq (all versions)
  - rhoso-operators/infra-rhel9-operator (all versions)
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-29T15:43:44.687454Z'
published: '2026-10-29'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T07:12:44.289Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-93007'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-93007'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2536076'
    label: RHBZ#2536076
tags:
  - cve.org
epss: 0.00427
epssPercentile: 0.36927
ingestedAt: '2026-11-03T10:42:03.630Z'
---

## Overview

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.

## Affected

- `rhceph/alloy-rhel10 (all versions)`
- `dnsmasq (all versions)`
- `dnsmasq (all versions)`
- `dnsmasq (all versions)`
- `dnsmasq (all versions)`
- `dnsmasq (all versions)`
- `openshift4/ose-baremetal-runtimecfg-rhel8 (all versions)`
- `openshift4/ose-baremetal-runtimecfg-rhel9 (all versions)`
- `openshift/ose-rhel-coreos-8 (all versions)`
- `openshift/ose-rhel-coreos-9 (all versions)`
- `openshift5/ose-baremetal-runtimecfg-rhel9 (all versions)`
- `openshift/ose-rhel-coreos-9 (all versions)`
- `dnsmasq (all versions)`
- `rhoso-operators/infra-rhel9-operator (all versions)`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

### Workarounds

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.