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VulnerabilityPublished Updated

CVE-2025-31115: tukaani-project xz · Race Condition Within a Thread

Affects tukaani-project xzSource CVE Database V5

0

Not known to be exploited · CVSS 8.7 High : upgrade to 5.8.1 soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 51% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 5.8.1, 5.8
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Apr 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade xz to 5.8.1; tukaani-project/xz to 5.8.

Affected software

ProductAffectedFixed in
tukaani-projectxzAffected
  • >=5.3.3alpha <5.8.1
Fixed in
  • 5.8.1
GitHubtukaani-project/xzpkg:github/tukaani-project/xzOther threatsAffected
  • <5.8
Fixed in
  • 5.8

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in XZ Utils version 5.8.1. Users and developers should upgrade to version 5.8.1 or later. For those unable to upgrade, standalone patches have been provided for all affected releases and should be applied. No vendor advisory indicates that no action is required or that the issue is already mitigated.

Description

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.

References

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