CVE-2026-106449 yawkat LZ4 Java: LZ4BlockInputStream with stopOnEmptyBlock=false recurses once per empty block, causing StackOverflowError
An attacker can cause a denial of service via stack exhaustion in the LZ4 Java library when configured to process empty blocks recursively.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-106449?
CVE-2026-106449 is a low-severity denial of service vulnerability in yawkat lz4-java, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
yawkat LZ4 Java provides LZ4 compression for Java. Prior to 1.11.4, net.jpountz.lz4.LZ4BlockInputStream configured with stopOnEmptyBlock set to false handles each well-formed empty LZ4Block by recursively calling refill(), allowing a long sequence of empty blocks in an attacker-controlled compressed stream to exhaust the decoding thread's stack and throw StackOverflowError. The default stopOnEmptyBlock setting is true and is not affected, and the issue does not cause memory corruption. This issue is fixed in version 1.11.4.
Weakness: CWE-674
Which versions are affected by CVE-2026-106449?
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 | All versions to 1.8.1 | None |
org.lz4:lz4-java Maven | All versions to 1.8.1 | None |
How do I fix CVE-2026-106449?
Upgrade at.yawk.lz4:lz4-java to 1.11.4 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-106449 being exploited?
There is no known exploitation of CVE-2026-106449 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-AB78638, CLEANSTART-2026-BO87876, CLEANSTART-2026-EA15585, CLEANSTART-2026-GW69718, CLEANSTART-2026-MS32897, CLEANSTART-2026-WC49025 and 43 more.