CVE-2026-106452 yawkat LZ4 Java: LZ4BlockInputStream allocates an unvalidated compressed length from the stream header
An attacker can cause a denial of service by sending a crafted LZ4 stream that triggers excessive memory allocation in the Java library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-106452?
CVE-2026-106452 is a medium-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 1.11.2, net.jpountz.lz4.LZ4BlockInputStream refill() validates that the compressedLen field in a legacy LZ4Block header is nonnegative but allocates a compressed-input buffer of that attacker-controlled size before reading payload data, allowing a header-only stream to request a near-2 GiB allocation and exhaust the JVM heap. Canonical writers emit raw blocks when compression is not smaller than the original block, but vulnerable readers accept non-canonical oversized compressed blocks. This issue is fixed in version 1.11.2.
Weakness: CWE-789
Which versions are affected by CVE-2026-106452?
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 | 1.11.2 |
at.yawk.lz4:lz4-java Maven | All versions | 1.11.2 |
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-2026-106452?
Upgrade at.yawk.lz4:lz4-java to 1.11.2 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-2026-106452 being exploited?
There is no known exploitation of CVE-2026-106452 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-CX61220, CLEANSTART-2026-ER27967, CLEANSTART-2026-GT24966, CLEANSTART-2026-HV49575, CLEANSTART-2026-HX04785, CLEANSTART-2026-OM13528 and 50 more.