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Ubuntu 25.10 XZ Utils Critical Denial of Service CVE-2026-34743

ubuntu
Calendar Grey June 2, 2026
Dist Ubuntu Esm H88
XZ Utils security advisory for Ubuntu addresses crash risks and execution flaws; essential updates required for protection.
XZ Utils could be made to crash or run programs as your login if it received specially crafted input.

Summary

XZ Utils could be made to crash or run programs as your login if it

received specially crafted input.

Software Description:

- xz-utils: XZ-format compression utilities

Details:

It was discovered that XZ Utils did not properly manage memory when

attempting to append data to a decoded index that contained no records.

An attacker could possibly use this issue to cause XZ Utils to crash,

resulting in a denial of service, or execute arbitrary code.

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu memory management xz-utils

Update Instructions

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

Ubuntu 25.10
  liblzma5                        5.8.1-1ubuntu0.1
  xz-utils                        5.8.1-1ubuntu0.1
  xzdec                           5.8.1-1ubuntu0.1

Ubuntu 24.04 LTS
  liblzma5                        5.6.1+really5.4.5-1ubuntu0.3
  xz-utils                        5.6.1+really5.4.5-1ubuntu0.3
  xzdec                           5.6.1+really5.4.5-1ubuntu0.3

Ubuntu 22.04 LTS
  liblzma5                        5.2.5-2ubuntu1.1
  xz-utils                        5.2.5-2ubuntu1.1
  xzdec                           5.2.5-2ubuntu1.1

Ubuntu 20.04 LTS
  liblzma5                        5.2.4-1ubuntu1.1+esm1
                                  Available with Ubuntu Pro
  xz-utils                        5.2.4-1ubuntu1.1+esm1
                                  Available with Ubuntu Pro
  xzdec                           5.2.4-1ubuntu1.1+esm1
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  liblzma5                        5.2.2-1.3ubuntu0.1+esm1
                                  Available with Ubuntu Pro
  xz-utils                        5.2.2-1.3ubuntu0.1+esm1
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  liblzma5                        5.1.1alpha+20120614-2ubuntu2.16.04.1+esm2
                                  Available with Ubuntu Pro
  xz-utils                        5.1.1alpha+20120614-2ubuntu2.16.04.1+esm2
                                  Available with Ubuntu Pro
  xzdec                           5.1.1alpha+20120614-2ubuntu2.16.04.1+esm2
                                  Available with Ubuntu Pro

Ubuntu 14.04 LTS
  liblzma5                        5.1.1alpha+20120614-2ubuntu2.14.04.1+esm2
                                  Available with Ubuntu Pro
  xz-utils                        5.1.1alpha+20120614-2ubuntu2.14.04.1+esm2
                                  Available with Ubuntu Pro
  xzdec                           5.1.1alpha+20120614-2ubuntu2.14.04.1+esm2
                                  Available with Ubuntu Pro

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

References

https://ubuntu.com/security/notices/USN-8362-1

CVE-2026-34743

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8362-1

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu memory management xz-utils

Package Information

https://launchpad.net/ubuntu/+source/xz-utils/5.8.1-1ubuntu0.1
https://launchpad.net/ubuntu/+source/xz-utils/5.6.1+really5.4.5-1ubuntu0.3
https://launchpad.net/ubuntu/+source/xz-utils/5.2.5-2ubuntu1.1

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