Heap-based buffer overflow in Unbound - CVE-2026-32792

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Main Vulnerability Database Vulnerabilities #VU131985

Heap-based buffer overflow in Unbound - CVE-2026-32792

Published: May 20, 2026


Vulnerability identifier: #VU131985
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-32792
CWE-ID: CWE-122
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 a heap-based buffer overflow in Unbound's DNSCrypt packet reading procedure when processing a crafted DNSCrypt query. A remote attacker can send a specially crafted DNSCrypt query to cause a denial of service.

Only installations compiled with DNSCrypt support are vulnerable. The crafted query's decrypted plaintext consists entirely of 0x00 bytes and lacks the expected 0x80 marker. A crash depends on the underlying memory allocator and memory layout.


Affected software

Unbound
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
Debian Linux
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server 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
FreeBSD
Ubuntu
SUSE Package Hub 15
Basesystem Module
openSUSE Leap
openEuler
Anolis OS
Fedora
LANTIME Operating System Firmware (LTOS)
unbound (Ubuntu package)
unbound-help
unbound-devel
unbound-debugsource
unbound-debuginfo
python3-unbound
unbound
unbound-libs
unbound-anchor
unbound-utils
unbound-anchor-debuginfo
libunbound8-debuginfo
libunbound8
libunbound-devel-mini-debugsource
unbound-munin
libunbound-devel-mini-debuginfo
unbound-python
libunbound-devel-mini
unbound-python-debuginfo
unbound (Debian package)

How to mitigate CVE-2026-32792

Install security update from vendor's website.

Unbound - update to 1.25.1
LANTIME Operating System Firmware (LTOS) - update to 7.10.012
unbound (Ubuntu package) - addressed in versions 1.4.22-1ubuntu4.14.04.3+esm3, 1.5.8-1ubuntu1.1+esm3, 1.6.7-1ubuntu2.6+esm4, 1.9.4-2ubuntu1.11+esm1, 1.13.1-1ubuntu5.15, 1.19.2-1ubuntu3.8, 1.22.0-2ubuntu2.3, 1.24.2-1ubuntu2.1
unbound-help - addressed in versions 1.11.0-23, 1.13.2-23, 1.17.1-17
unbound-devel - addressed in versions 1.11.0-23, 1.13.2-23, 1.17.1-17
unbound-debugsource - addressed in versions 1.11.0-23, 1.13.2-23, 1.17.1-17
unbound-debuginfo - addressed in versions 1.11.0-23, 1.13.2-23, 1.17.1-17
python3-unbound - addressed in versions 1.11.0-23, 1.13.2-23, 1.17.1-17
unbound - addressed in versions 1.11.0-23, 1.13.2-23, 1.17.1-17
unbound-libs - addressed in versions 1.11.0-23, 1.13.2-23, 1.17.1-17
unbound-anchor - addressed in versions 1.13.2-23, 1.17.1-17
python3-unbound - update to 1.17.1-11
unbound - update to 1.17.1-11
unbound-utils - update to 1.17.1-11
unbound-libs - update to 1.17.1-11
unbound-devel - update to 1.17.1-11
unbound-anchor - update to 1.17.1-11
unbound-utils - update to 1.17.1-17
unbound-anchor-debuginfo - addressed in versions 1.20.0-150100.10.25.1, 1.20.0-150600.23.16.1
unbound-devel - addressed in versions 1.20.0-150100.10.25.1, 1.20.0-150600.23.16.1
libunbound8-debuginfo - addressed in versions 1.20.0-150100.10.25.1, 1.20.0-150600.23.16.1
unbound-anchor - addressed in versions 1.20.0-150100.10.25.1, 1.20.0-150600.23.16.1
unbound-debugsource - addressed in versions 1.20.0-150100.10.25.1, 1.20.0-150600.23.16.1
libunbound8 - addressed in versions 1.20.0-150100.10.25.1, 1.20.0-150600.23.16.1
unbound-debuginfo - addressed in versions 1.20.0-150100.10.25.1, 1.20.0-150600.23.16.1
libunbound-devel-mini-debugsource - update to 1.20.0-150600.23.16.1
unbound-munin - update to 1.20.0-150600.23.16.1
unbound - update to 1.20.0-150600.23.16.1
libunbound-devel-mini-debuginfo - update to 1.20.0-150600.23.16.1
unbound-python - update to 1.20.0-150600.23.16.1
libunbound-devel-mini - update to 1.20.0-150600.23.16.1
unbound-python-debuginfo - update to 1.20.0-150600.23.16.1
unbound (Debian package) - update to 1.22.0-2+deb13u3
unbound - addressed in versions 1.25.1-1.fc43, 1.25.1-1.fc44

External References

Related Security Bulletins