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Gentoo Linux Security Advisory                           GLSA 202504-01
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                                           https://security.gentoo.org/
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 Severity: Normal
    Title: XZ Utils: Use after free
     Date: April 05, 2025
     Bugs: #953086
       ID: 202504-01

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Synopsis
========

A vulnerability has been discovered in XZ Utils, which could lead to
denial of service.

Background
==========

XZ Utils is free general-purpose data compression software with a high
compression ratio.

Affected packages
=================

Package            Vulnerable    Unaffected
-----------------  ------------  ------------
app-arch/xz-utils  < 5.6.4-r1    >= 5.6.4-r1

Description
===========

A use-after-free has been discovered in XZ utils. Please review the CVE
identifier referenced below for details.

Impact
======

The multithreaded .xz decoder in liblzma has a bug where invalid input
can at least result in a crash. The effects include heap use after free
and writing to an address based on the null pointer plus an offset.
Applications and libraries that use the lzma_stream_decoder_mt function
are affected.

It's unlikely one can achieve more than a crash if xz is built with PIE
on a 64-bit system especially, as is done in Gentoo by default.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All XZ utils users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=app-arch/xz-utils-5.6.4-r1"

References
==========

[ 1 ] CVE-2025-31115
      https://nvd.nist.gov/vuln/detail/CVE-2025-31115

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

 https://security.gentoo.org/glsa/202504-01

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users' machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
https://bugs.gentoo.org.

License
=======

Copyright 2025 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

https://creativecommons.org/licenses/by-sa/2.5