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[USN-8873-1] Unbound vulnerabilities

Posted on 06 October 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8873-1
October 06, 2026

unbound vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in Unbound.

Software Description:
- unbound: validating, recursive, caching DNS resolver

Details:

Yuqi Qiu and Xiang Li discovered that Unbound did not correctly handle
certain memory operations. An attacker could possibly use this issue to
cause a denial of service or execute arbitrary code. (CVE-2026-81642)

Ben Morris discovered that Unbound did not correctly handle certain
memory operations. An attacker could possibly use this issue to cause a
denial of service or execute arbitary code. (CVE-2026-82717)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
libunbound8 1.24.2-1ubuntu2.3
python3-unbound 1.24.2-1ubuntu2.3
unbound 1.24.2-1ubuntu2.3

Ubuntu 24.04 LTS
libunbound8 1.19.2-1ubuntu3.10
python3-unbound 1.19.2-1ubuntu3.10
unbound 1.19.2-1ubuntu3.10

Ubuntu 22.04 LTS
libunbound8 1.13.1-1ubuntu5.16
python3-unbound 1.13.1-1ubuntu5.16
unbound 1.13.1-1ubuntu5.16

Ubuntu 20.04 LTS
libunbound8 1.9.4-2ubuntu1.11+esm2
Available with Ubuntu Pro
python-unbound 1.9.4-2ubuntu1.11+esm2
Available with Ubuntu Pro
python3-unbound 1.9.4-2ubuntu1.11+esm2
Available with Ubuntu Pro
unbound 1.9.4-2ubuntu1.11+esm2
Available with Ubuntu Pro

Ubuntu 18.04 LTS
libunbound2 1.6.7-1ubuntu2.6+esm5
Available with Ubuntu Pro
python-unbound 1.6.7-1ubuntu2.6+esm5
Available with Ubuntu Pro
python3-unbound 1.6.7-1ubuntu2.6+esm5
Available with Ubuntu Pro
unbound 1.6.7-1ubuntu2.6+esm5
Available with Ubuntu Pro

Ubuntu 16.04 LTS
libunbound2 1.5.8-1ubuntu1.1+esm4
Available with Ubuntu Pro
python-unbound 1.5.8-1ubuntu1.1+esm4
Available with Ubuntu Pro
unbound 1.5.8-1ubuntu1.1+esm4
Available with Ubuntu Pro

Ubuntu 14.04 LTS
libunbound2 1.4.22-1ubuntu4.14.04.3+esm4
Available with Ubuntu Pro
python-unbound 1.4.22-1ubuntu4.14.04.3+esm4
Available with Ubuntu Pro
unbound 1.4.22-1ubuntu4.14.04.3+esm4
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8873-1
CVE-2026-81642, CVE-2026-82717

Package Information:
https://launchpad.net/ubuntu/+source/unbound/1.24.2-1ubuntu2.3
https://launchpad.net/ubuntu/+source/unbound/1.19.2-1ubuntu3.10
https://launchpad.net/ubuntu/+source/unbound/1.13.1-1ubuntu5.16

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