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Fencer Vulns
medium 5.3

CVE-2026-80225 json

Possible degradation of service from continuous queries on the same TCP/DoT connection

published 2026-09-16 53 d ago modified 2026-09-23 46 d ago also EUVD-2026-80289

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

In NLnetLabs Unbound up to and including 1.26.0, a degradation of service vulnerability is present in the TCP/DoT reading procedure where there is no limit on consecutive reads. A malicious actor that can stream and sustain a rate of distinct uncached names over the TCP/DoT connection, monopolizes a single worker's entire event loop for as long as its writes stay ahead of the drain.

Patch / fix

  • NLnet Labs Unbound 1.26.1
  • unbound Debian 13 1.26.1-0+deb13u1
  • unbound Debian 14 1.26.1-1

debian advisories DEBIAN-CVE-2026-80225

  • unbound Ubuntu 22.04 LTS 1.13.1-1ubuntu5.17
  • unbound Ubuntu 24.04 LTS 1.19.2-1ubuntu3.12
  • unbound Ubuntu 26.04 LTS 1.24.2-1ubuntu2.4
  • unbound Ubuntu Pro 20.04 LTS 1.9.4-2ubuntu1.11+esm3

ubuntu advisories UBUNTU-CVE-2026-80225

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • unbound hummingbird 1 1.26.1-1.hum1
  • unbound-libs hummingbird 1 1.26.1-1.hum1
  • unbound-munin hummingbird 1 1.26.1-1.hum1
  • unbound-utils hummingbird 1 1.26.1-1.hum1
  • unbound-anchor hummingbird 1 1.26.1-1.hum1
  • unbound-dracut hummingbird 1 1.26.1-1.hum1
  • python3-unbound hummingbird 1 1.26.1-1.hum1

red hat advisories RHSA-2026:68590

  • unbound Linux Micro 6.1 1.26.1-slfo.1.1_1.1
  • unbound SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +6 more 1.26.1-150100.10.31.1
  • unbound SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Package Hub 15 SP7 +1 more 1.26.1-150600.23.24.1
  • unbound SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 1.26.1-160000.1.1
  • unbound Linux Micro 6.0 1.26.1-159998.1.1

suse advisories SUSE-SU-2026:24376-1SUSE-SU-2026:4624-1SUSE-SU-2026:4620-1SUSE-SU-2026:24128-1SUSE-SU-2026:24226-1SUSE-SU-2026:24135-1

  • unbound openSUSE Leap 16.0 1.26.1-160000.1.1
  • unbound openSUSE Tumbleweed 1.26.1-1.1

opensuse advisories openSUSE-SU-2026:22082-1openSUSE-SU-2026:11930-1

  • unbound Azure Linux 3.0 1.26.1-1

azure linux advisories AZL-101724

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-80225 updated cvss 5.3

unbound: Unbound: Denial of Service via continuous queries on TCP/DoT connection

  • Red Hat Enterprise Linux 6 unbound, unbound-libs, unbound-python
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 unbound, unbound-libs, unbound-python Red Hat Enterprise Linux 8 unbound, unbound-libs, python3-unbound Red Hat Enterprise Linux 9 unbound, unbound-libs, unbound-dracut, python3-unbound Red Hat Enterprise Linux 10 unbound Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images unbound 1.26.1-1.hum1, unbound-libs 1.26.1-1.hum1, unbound-munin 1.26.1-1.hum1, unbound-utils 1.26.1-1.hum1, unbound-anchor 1.26.1-1.hum1, unbound-dracut 1.26.1-1.hum1, +1 more
    fixed: vendor fix RHSA-2026:68590

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
53 d ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • NLnet Labs Unbound

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.