Resource exhaustion in Unbound - CVE-2026-80225

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Main Vulnerability Database Vulnerabilities #VU150191

Resource exhaustion in Unbound - CVE-2026-80225

Published: September 16, 2026 / Updated: September 19, 2026


Vulnerability identifier: #VU150191
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-80225
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to uncontrolled resource consumption in Unbound's TCP/DoT reading procedure when processing a sustained stream of distinct uncached names over a TCP/DoT connection. A remote attacker can stream distinct uncached names at a sustained rate to cause a denial of service.


Affected software

Unbound
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP6
Debian Linux
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Micro
Ubuntu
Basesystem Module
SUSE Package Hub 15
openSUSE Leap
openEuler
Anolis OS
Fedora
libunbound2 (Ubuntu package)
unbound (Ubuntu package)
libunbound8 (Ubuntu package)
unbound
python3-unbound
unbound-anchor
unbound-debuginfo
unbound-debugsource
unbound-devel
unbound-help
unbound-libs
unbound-utils
unbound-anchor-debuginfo
libunbound8-debuginfo
libunbound8
unbound-munin
libunbound-devel-mini-debuginfo
unbound-python-debuginfo
unbound-python
libunbound-devel-mini
libunbound-devel-mini-debugsource
unbound (Debian package)

How to mitigate CVE-2026-80225

Install security update from vendor's website.

Unbound - update to 1.26.1
libunbound2 (Ubuntu package) - addressed in versions 1.4.22-1ubuntu4.14.04.3+esm5, 1.5.8-1ubuntu1.1+esm5, 1.6.7-1ubuntu2.6+esm6
unbound (Ubuntu package) - addressed in versions 1.4.22-1ubuntu4.14.04.3+esm5, 1.5.8-1ubuntu1.1+esm5, 1.6.7-1ubuntu2.6+esm6, 1.9.4-2ubuntu1.11+esm3, 1.13.1-1ubuntu5.17, 1.19.2-1ubuntu3.12, 1.24.2-1ubuntu2.4
libunbound8 (Ubuntu package) - addressed in versions 1.9.4-2ubuntu1.11+esm3, 1.13.1-1ubuntu5.17, 1.19.2-1ubuntu3.12, 1.24.2-1ubuntu2.4
unbound - addressed in versions 1.13.2-28, 1.17.1-22
python3-unbound - addressed in versions 1.13.2-28, 1.17.1-22
unbound-anchor - addressed in versions 1.13.2-28, 1.17.1-22
unbound-debuginfo - addressed in versions 1.13.2-28, 1.17.1-22
unbound-debugsource - addressed in versions 1.13.2-28, 1.17.1-22
unbound-devel - addressed in versions 1.13.2-28, 1.17.1-22
unbound-help - addressed in versions 1.13.2-28, 1.17.1-22
unbound-libs - addressed in versions 1.13.2-28, 1.17.1-22
python3-unbound - update to 1.17.1-21
unbound-libs - update to 1.17.1-21
unbound-devel - update to 1.17.1-21
unbound-anchor - update to 1.17.1-21
unbound-utils - update to 1.17.1-21
unbound - update to 1.17.1-21
unbound-utils - update to 1.17.1-22
unbound - addressed in versions 1.26.1-1.fc43, 1.26.1-1.fc44, 1.26.1-1.fc45
unbound-anchor-debuginfo - addressed in versions 1.26.1-150100.10.31.1, 1.26.1-150600.23.24.1
libunbound8-debuginfo - addressed in versions 1.26.1-150100.10.31.1, 1.26.1-150600.23.24.1
unbound-debugsource - addressed in versions 1.26.1-150100.10.31.1, 1.26.1-150600.23.24.1
unbound-anchor - addressed in versions 1.26.1-150100.10.31.1, 1.26.1-150600.23.24.1
unbound-debuginfo - addressed in versions 1.26.1-150100.10.31.1, 1.26.1-150600.23.24.1
unbound-devel - addressed in versions 1.26.1-150100.10.31.1, 1.26.1-150600.23.24.1
libunbound8 - addressed in versions 1.26.1-150100.10.31.1, 1.26.1-150600.23.24.1
unbound-munin - update to 1.26.1-150600.23.24.1
libunbound-devel-mini-debuginfo - update to 1.26.1-150600.23.24.1
unbound-python-debuginfo - update to 1.26.1-150600.23.24.1
unbound-python - update to 1.26.1-150600.23.24.1
unbound - update to 1.26.1-150600.23.24.1
libunbound-devel-mini - update to 1.26.1-150600.23.24.1
libunbound-devel-mini-debugsource - update to 1.26.1-150600.23.24.1
unbound (Debian package) - update to 1.26.1-0+deb13u1

External References

Related Security Bulletins