# CVE-2025-66566: lz4-java: yawkat LZ4 Java provides LZ4 compression for Java

CVE-2025-66566 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2025-66566, released December 5, 2025. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2025-66566
- Priority: High
- CVSS: 7.5 (Important)
- EPSS: 0.0065
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Dec 5, 2025

## Description

yawkat LZ4 Java provides LZ4 compression for Java. Insufficient clearing of the output buffer in Java-based decompressor implementations in lz4-java 1.10.0 and earlier allows remote attackers to read previous buffer contents via crafted compressed input. In applications where the output buffer is reused without being cleared, this may lead to disclosure of sensitive data. JNI-based implementations are not affected. This vulnerability is fixed in 1.10.1.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | jmc RHEL 9 | 0:8.2.0-19.el9_8.2 | [RHSA-2026:20568](https://patchblox.com/security/data/fix/linux/rhsa-2026-20568.md) | Mar 12, 2026 |
| Linux | jmc almalinux 9 | 8.2.0-19.el9_8.2 | [ALSA-2026:20568](https://patchblox.com/security/data/fix/linux/alsa-2026-20568.md) | May 26, 2026 |
| Linux | jmc ol 9 | 0:8.2.0-18.el9_7.2 | [ELSA-2026-0752](https://patchblox.com/security/data/fix/linux/elsa-2026-0752.md) | Jan 19, 2026 |
| Linux | jmc rocky 9 | 0:8.2.0-19.el9_8.2 | [RLSA-2026:20568](https://patchblox.com/security/data/fix/linux/rlsa-2026-20568.md) | May 30, 2026 |
| Linux | lz4-java Debian 14 | 1.11.2+ds1-1 | [DEBIAN-CVE-2025-66566](https://patchblox.com/security/data/fix/linux/debian-cve-2025-66566.md) | Dec 5, 2025 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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