yawkat LZ4 Java: Native library extraction to a shared temporary directory is vulnerable to file replacement by another local user

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.3 · CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-106451: 0.11% estimated exploitation activity in the next 30 days; percentile 1.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary When no system-installed liblz4-java is found, net.jpountz.util.Native.load() extracts the bundled native library to java.io.tmpdir and loads it with System.load. The path of the extracted library can be predicted before it is created, and the library file is opened without exclusive creation. Another local user who can write to the same temporary directory can therefore create the file first and control the code that is loaded. Details Only the .lck file is created safely, with a random name and exclusive creation. The library path is the .lck name without the .lck suffix, and nothing reserves it. new FileOutputStream(tempLib) opens it with OCREAT|OTRUNC and follows symlinks. In a shared, world-writable temporary directory, another user can watch for the .lck file and create the corresponding library file before it is opened. If they win that race, they own the file. The victim then writes into the attacker-owned file, and the attacker can overwrite it again before…

Published by the source

7 Oct 2026, 20:35 UTC

Last modified by the source

7 Oct 2026, 20:45 UTC

Source last checked

26 Oct 2026, 16:58 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mcr4-qmvw-px4g

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mcr4-qmvw-px4g

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# Patch Next advisory brief: CVE-2026-106451

Advisory: yawkat LZ4 Java: Native library extraction to a shared temporary directory is vulnerable to file replacement by another local user
IDs: CVE-2026-106451, GHSA-mcr4-qmvw-px4g
Record: https://patchnext.com/advisories/cve-2026-106451 (revision 3, source checked 26 Oct 2026, 16:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: at.yawk.lz4:lz4-java 1.11.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven at.yawk.lz4:lz4-java: affected <= 1.11.3; fixed in 1.11.4
- Maven org.lz4:lz4-java: affected >= 1.7.0, <= 1.8.1

## Suggested inspection (read-only)
- Maven at.yawk.lz4:lz4-java: check the installed version with your package manager.
- Maven org.lz4:lz4-java: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on at.yawk.lz4:lz4-java, org.lz4:lz4-java.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-mcr4-qmvw-px4g (OSV record GHSA-mcr4-qmvw-px4g lists affected ranges: Maven at.yawk.lz4:lz4-java >=0 =1.7.0 <=1.8.1)
- Verified: https://github.com/advisories/GHSA-mcr4-qmvw-px4g (GitHub-reviewed advisory GHSA-mcr4-qmvw-px4g lists affected ranges: Maven at.yawk.lz4:lz4-java >=0 =1.7.0 <=1.8.1)

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