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Advisory record · GHSA-cmp6-m4wj-q63q

yawkat LZ4 Java has a possible information leak in Java safe decompressor

CVSS 8.2 HighEPSS 0.0065 · 51st percentile

Published by the GitHub Advisory Database at 5 Dec 2025, 18:54 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
at.yawk.lz4:lz4-javaMaven<1.10.11.10.1
org.lz4:lz4-javaMaven<=1.8.1No fixed version yet
org.lz4:lz4-pure-javaMaven<=1.8.1No fixed version yet
net.jpountz.lz4:lz4Maven<=1.8.1No fixed version yet
Identifiers
GHSA-cmp6-m4wj-q63q · CVE-2025-66566
Weakness (CWE)
CWE-201
Tags
Published
5 Dec 2025
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Affected versions of at.yawk.lz4:lz4-java are below 1.10.1, and the Maven org.lz4:lz4-java, org.lz4:lz4-pure-java and net.jpountz.lz4:lz4 packages at 1.8.1 and earlier have no fixed version listed. A remote attacker who supplies crafted compressed input can make the Java-based decompressors read previously stored contents of a reused output buffer, which may disclose sensitive data. Upgrade at.yawk.lz4:lz4-java to 1.10.1; if that is not possible, zero the output buffer before each decompression call.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.2 High 4.0 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0065, the 51st percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:17 UTC First seen by agentprime
  2. 31 Oct 2026, 14:17 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.