[USN-8705-2] OpenZFS vulnerability

[noreply+usn-bot at canonical.com]

==========================================================================
Ubuntu Security Notice USN-8705-2
August 31, 2026

zfs-linux vulnerability
==========================================================================

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

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

OpenZFS could be made to run programs as an administrator.

Software Description:
- zfs-linux: OpenZFS file system for Linux

Details:

USN-8705-1 fixed vulnerabilities in OpenZFS. This update provides the
corresponding fix for OpenZFS on Ubuntu 18.04 LTS and Ubuntu 20.04 LTS.

Original advisory details:

It was discovered that OpenZFS incorrectly handled authorization checks for
certain ioctl operations on Linux. A local attacker could possibly use this
issue to perform pool-administrative operations or access privileged
information, resulting in an authorization bypass.

Update instructions:

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

Ubuntu 20.04 LTS
  libuutil1linux                  0.8.3-1ubuntu12.18+esm1
                                  Available with Ubuntu Pro
  libzfs2linux                    0.8.3-1ubuntu12.18+esm1
                                  Available with Ubuntu Pro
  zfs-dkms                        0.8.3-1ubuntu12.18+esm1
                                  Available with Ubuntu Pro
  zfsutils-linux                  0.8.3-1ubuntu12.18+esm1
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  libuutil1linux                  0.7.5-1ubuntu16.12+esm1
                                  Available with Ubuntu Pro
  libzfs2linux                    0.7.5-1ubuntu16.12+esm1
                                  Available with Ubuntu Pro
  zfs-dkms                        0.7.5-1ubuntu16.12+esm1
                                  Available with Ubuntu Pro
  zfsutils-linux                  0.7.5-1ubuntu16.12+esm1
                                  Available with Ubuntu Pro

After a standard system update you need to reboot your computer to make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-8705-2
  https://ubuntu.com/security/notices/USN-8705-1
  CVE-2026-79619
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