CVE-2026-106451 yawkat LZ4 Java: Native library extraction to a shared temporary directory is vulnerable to file replacement by another local user
A local attacker can exploit a race condition in native library extraction to replace the library file, potentially executing arbitrary code as the victim.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-106451?
CVE-2026-106451 is a high-severity vulnerability in yawkat lz4-java, published on 6 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
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.
Which versions are affected by CVE-2026-106451?
4 open source packages ship an affected version, including at.yawk.lz4:lz4-java and org.lz4:lz4-java.
| Package | Affected | Fixed in |
|---|---|---|
at.yawk.lz4:lz4-java Maven | All versions | 1.11.4 |
at.yawk.lz4:lz4-java Maven | All versions | 1.11.4 |
org.lz4:lz4-java Maven | From 1.7.0 to 1.8.1 | None |
org.lz4:lz4-java Maven | From 1.7.0 to 1.8.1 | None |
How do I fix CVE-2026-106451?
Upgrade at.yawk.lz4:lz4-java to 1.11.4 or later.
Is CVE-2026-106451 being exploited?
There is no known exploitation of CVE-2026-106451 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-IA44862, CLEANSTART-2026-KU71354, CLEANSTART-2026-OZ05879, CLEANSTART-2026-TX68944, CLEANSTART-2026-WI71078, CLEANSTART-2026-XP90287 and 44 more.