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Fencer Vulns
medium 5.6

CVE-2025-31115 json

XZ has a heap-use-after-free bug in threaded .xz decoder

published 2025-04-03 19 mo ago modified 2026-10-15 25 d ago also EUVD-2025-14786 , GHSA-6cc8-p5mm-29w2 , HSEC-2025-0003

cvss
5.6
version 3.1, OSV
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
0
none known

Summary

XZ Utils provide a general-purpose data-compression library plus command-line tools. In XZ Utils 5.3.3alpha to 5.8.0, 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. The bug has been fixed in XZ Utils 5.8.1, and the fix has been committed to the v5.4, v5.6, v5.8, and master branches in the xz Git repository. No new release packages will be made from the old stable branches, but a standalone patch is available that applies to all affected releases.

Patch / fix

  • hackage xz-clib 5.8.1
  • tukaani xz 5.8.1
  • xz-utils Debian 12 5.4.1-1
  • xz-utils Debian 14, Debian 13 5.8.1-1

debian advisories DEBIAN-CVE-2025-31115

  • xz-utils Ubuntu 24.04 LTS 5.6.1+really5.4.5-1ubuntu0.2

ubuntu advisories UBUNTU-CVE-2025-31115

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • xz RHEL 10.0 1:5.6.2-4.el10_0
  • xz-libs RHEL 10.0 1:5.6.2-4.el10_0
  • xz-lzma-compat RHEL 10.0 1:5.6.2-4.el10_0

red hat advisories RHSA-2025:7524

  • xz Linux Micro 6.1 5.4.3-slfo.1.1_2.1
  • xz Linux Micro 6.0 5.4.3-5.1
  • xz SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 5.4.1-150600.3.3.1

suse advisories SUSE-SU-2025:20590-1SUSE-SU-2025:20553-1SUSE-SU-2025:1137-1

  • xz openSUSE Tumbleweed 5.8.1-1.1

opensuse advisories openSUSE-SU-2025:14984-1

  • xz AlmaLinux 10 1:5.6.2-4.el10_0
  • xz-libs AlmaLinux 10 1:5.6.2-4.el10_0
  • xz-lzma-compat AlmaLinux 10 1:5.6.2-4.el10_0

almalinux advisories ALSA-2025:7524

  • xz Rocky Linux 10 1:5.6.2-4.el10_0

rocky linux advisories RLSA-2025:7524

  • xz Alpine 3.18 5.4.3-r1
  • xz Alpine 3.19 5.4.5-r1
  • xz Alpine 3.20 5.6.2-r1
  • xz Alpine 3.21 5.6.3-r1
  • xz Alpine 3.24, Alpine 3.23, Alpine 3.22 5.8.1-r0

alpine advisories ALPINE-CVE-2025-31115

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • xz Azure Linux 3.0 5.4.4-2

azure linux advisories AZL-59497

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • xz Arch Linux 5.8.1-1
  • lib32-xz Arch Linux 5.8.1-1

arch linux advisories AVG-2860AVG-2861

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-31115 updated cvss 7.5

xz: XZ has a heap-use-after-free bug in threaded .xz decoder

  • Red Hat Enterprise Linux 6 xz, xz-libs, xz-lzma-compat
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 10) xz-lzma-compat 5.6.2-4.el10_0 Red Hat Enterprise Linux BaseOS (v. 10) xz 5.6.2-4.el10_0, xz-libs 5.6.2-4.el10_0
    fixed: vendor fix RHSA-2025:7524
  • Red Hat Enterprise Linux 7 xz, xz-libs, xz-compat-libs, xz-lzma-compat Red Hat Enterprise Linux 8 xz, xz-libs, xz-lzma-compat Red Hat Enterprise Linux 9 xz, xz-libs, xz-lzma-compat Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-26-181-05 updated cvss 7.5

XZ Utils vulnerability impacting B&R Products

  • B&R Industrial Automation GmbH C50 <1.8.0 B&R Industrial Automation GmbH C80 <1.8.0 B&R Industrial Automation GmbH FT50 <1.8.1 B&R Industrial Automation GmbH MT50 <1.8.1 B&R Industrial Automation GmbH PPC3100 <1.8.1 B&R Industrial Automation GmbH T30 <1.8.0
    +2 more products
    B&R Industrial Automation GmbH T50 <1.8.1 B&R Industrial Automation GmbH T80 <1.8.0
    affected: vendor fix, mitigation
  • B&R Industrial Automation GmbH C50 1.8.0 B&R Industrial Automation GmbH C80 1.8.0 B&R Industrial Automation GmbH FT50 1.8.1 B&R Industrial Automation GmbH MT50 1.8.1 B&R Industrial Automation GmbH PPC3100 1.8.1 B&R Industrial Automation GmbH T30 1.8.0
    +2 more products
    B&R Industrial Automation GmbH T50 1.8.1 B&R Industrial Automation GmbH T80 1.8.0
    fixed

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-25-162-05 updated cvss 7.5

Siemens SIMATIC S7-1500 CPU family

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.5
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
19 mo ago

Exploit prediction

0.68% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 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
CNA 4.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
OSV 3.1 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Affected packages

ecosystem package affected fixed in
hackage xz-clib
>=5.6.3, <5.8.1
5.8.1

Affected products

  • tukaani-project xz
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-366 Race Condition within a Thread
  • CWE-416 Use After Free
  • CWE-476 NULL Pointer Dereference
  • CWE-826 Premature Release of Resource During Expected Lifetime

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.