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CWE-366Weakness · CWE-366

CVE-2025-31115

HIGH · 8.7 CVSS v4.0 Published 2025-04-03
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
96/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix High confidence

XZ Utils 5.8.1 (or later)

  1. Identify the current installed version of XZ Utils using `xz --version` or checking your system's package manager
  2. Upgrade XZ Utils to version 5.8.1 or later using your system's package manager or from source
  3. For systems using the multithreaded decoder (lzma_stream_decoder_mt function), verify the upgrade was successful by checking the version
  4. If your distribution does not have 5.8.1 available yet, consider building from source using the v5.8 branch or applying the standalone patch referenced in the security advisory
  5. Rebuild any applications that statically link against liblzma to ensure they use the fixed library
Caveat Minimal risk - this is a bug fix for a crash/heap corruption issue; ensure any custom code using lzma_stream_decoder_mt handles the function return values properly after upgrade

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-31115 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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