Vulnerability · Published Oct 6, 2026 · Assigned by GitHub_M

CVE-2026-106451yawkat LZ4 Java: Native library extraction to a shared temporary directory is vulnerable to file replacement by another local user

High 7.3

In plain English

A high-severity security flaw in lz4-java from yawkat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)7.3High

Exploit odds (30 days)0.1%top 98.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

yawkat LZ4 Java provides LZ4 compression for Java. From 1.7.0 until 1.11.4, net.jpountz.util.Native.load() uses File.createTempFile to create an exclusive temporary .lck file but derives the native-library path by removing the suffix, then FileOutputStream opens that predictable path without exclusive creation, allowing another local user with access to the same shared temporary directory to create or replace the library file before System.load() uses it. Successful exploitation depends on shared-directory permissions, host protections, and winning the race, and can execute native code as the victim; hardened systems may instead cause library loading to fail and fall back to Java implementations. Configurations using a system library, a private java.io.tmpdir, or Java-only implementations are not affected. This issue is fixed in version 1.11.4.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	lz4-java	no fix listed	DEBIAN-CVE-2026-106451
Debian:13	lz4-java	no fix listed	DEBIAN-CVE-2026-106451
Debian:14	lz4-java	no fix listed	DEBIAN-CVE-2026-106451
Maven	at.yawk.lz4:lz4-java	1.11.4	GHSA-mcr4-qmvw-px4g
Maven	org.lz4:lz4-java	no fix listed	GHSA-mcr4-qmvw-px4g
Ubuntu:22.04:LTS	lz4-java	no fix listed	UBUNTU-CVE-2026-106451
Ubuntu:24.04:LTS	lz4-java	no fix listed	UBUNTU-CVE-2026-106451
Ubuntu:26.04:LTS	lz4-java	no fix listed	UBUNTU-CVE-2026-106451
Ubuntu:26.10	lz4-java	no fix listed	UBUNTU-CVE-2026-106451

Affected products (as reported)

Vendor	Product	Versions
yawkat	lz4-java	< 1.11.4

Weakness: CWE-367, CWE-377 · Vector: 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

References

https://github.com/yawkat/lz4-java/security/advisories/GHSA-mcr4-qmvw-px4g x_refsource_CONFIRM
https://github.com/yawkat/lz4-java/commit/7a48b7f6b8099b9dab6541e4ac2ee0979dc55aa3 x_refsource_MISC
https://github.com/yawkat/lz4-java/releases/tag/v1.11.4 x_refsource_MISC