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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Ceph Storage 9 | — | — |
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 5 | — | — |
| Red Hat | Red Hat OpenStack Platform 13 (Queens) | — | — |
| Red Hat | Red Hat OpenStack Platform 18.0 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | dnsmasq | No fix yet | — |
| Debian 13 | dnsmasq | No fix yet | — |
| Debian 12 | dnsmasq | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | dnsmasq | No fix yet | — |
| Ubuntu 26.04 LTS | dnsmasq | No fix yet | — |
| Ubuntu 24.04 LTS | dnsmasq | No fix yet | — |
| Ubuntu 22.04 LTS | dnsmasq | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | dnsmasq | No fix yet | — |
| Ubuntu Pro 18.04 LTS | dnsmasq | No fix yet | — |
| Ubuntu Pro 16.04 LTS | dnsmasq | No fix yet | — |
| Ubuntu Pro 14.04 LTS | dnsmasq | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | dnsmasq | 2.93-3.1 | openSUSE-SU-2026:12415-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | dnsmasq | No fix yet | — |
Advisories 2
- openSUSE-SU-2026:12415-1 dnsmasq-2.93-3.1 on GA media SUSE / openSUSE Security Updates · Nov 5, 2026
- WID-SEC-2026-4256 dnsmasq: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 29, 2026
References
- https://access.redhat.com/security/cve/CVE-2026-93007 vdb-entry
- RHBZ#2536076 issue-tracking