Summary
yawkat LZ4 Java: LZ4DecompressorWithLength allocates the unvalidated size from the 4-byte length header, so a 5-byte input triggers a 1 GiB allocation and OutOfMemoryError
LZ4DecompressorWithLength.decompress(byte[], int) allocates whatever size the 4-byte length header declares, before it reads a single byte of compressed data. A 5-byte input whose header says 0x40000000 makes the JVM commit a gigabyte and can cause heap exhaustion.
Details
net.jpountz.lz4.LZ4DecompressorWithLength reads the header and passes it straight on:
final int destLen = getDecompressedLength(src, srcOff);
return fastDecompressor.decompress(src, srcOff + 4, destLen);
and net.jpountz.lz4.LZ4FastDecompressor allocates it:
public final byte[] decompress(byte[] src, int srcOff, int destLen) {
final byte[] decompressed = new byte[destLen];
decompress(src, srcOff, decompressed, 0, destLen);
return decompressed;
}
getDecompressedLength performs no validation: no comparison against src.length, no ceiling, no rejection of negatives. LZ4SafeDecompressor.decompress(byte[], int, int, int) has the same shape with maxDestLen.
The sibling overload that callers pass their own buffer to, decompress(src, srcOff, dest, destOff, destLen), is fine, because there destLen is chosen by the caller rather than by the input. The bug is specific to the convenience overloads that take the size from the header, and that difference is the whole finding.
Impact
Any application that decompresses attacker-supplied LZ4 frames through the with-length convenience API can be made to allocate up to 2 GiB per call from a 5-byte message. On a service that decompresses request bodies, a few concurrent 5-byte requests exhaust the heap. No privileges are needed, only the ability to get bytes into the decompressor. Confidentiality and integrity are untouched.
CVE-2026-106453 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.11.2); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-106453? CVE-2026-106453 is a medium-severity security vulnerability in at.yawk.lz4:lz4-java (maven), affecting versions <= 1.11.1. It is fixed in 1.11.2.
- How severe is CVE-2026-106453? CVE-2026-106453 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by CVE-2026-106453?
at.yawk.lz4:lz4-java(maven) (versions <= 1.11.1)org.lz4:lz4-java(maven) (versions <= 1.8.1)
- Is there a fix for CVE-2026-106453? Yes. CVE-2026-106453 is fixed in 1.11.2. Upgrade to this version or later.
- Is CVE-2026-106453 exploitable, and should I be worried? Whether CVE-2026-106453 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-106453 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-106453? Upgrade
at.yawk.lz4:lz4-javato 1.11.2 or later.