What is the CVSS score of CVE-2025-66566?

CVE-2025-66566 has a CVSS 4.0 base score of 8.2 (High). CVSS vector: 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. EPSS exploitation probability: 0.1%.

Which versions of Java are affected by CVE-2025-66566?

CVE-2025-66566 affects yawkat LZ4 Java library versions 1.10.0 and earlier, allowing attackers to extract sensitive data from memory buffers in applications that reuse decompression buffers without…. A patch is available.

How to fix or mitigate CVE-2025-66566?

Within 24 hours: Inventory all applications using lz4-java library and identify those running versions 1.10.0 or earlier; assess whether output buffers are reused without clearing. Within 7 days: Upgrade to lz4-java 1.10.1 or later for all affected applications, or implement buffer clearing logic if upgrade is not immediately feasible. Within 30 days: Validate all upgrades in production, conduct code review of custom decompression implementations to ensure proper buffer handling, and monitor for any exploitation attempts in application logs.

Java CVE-2025-66566

EUVD-2025-201456 HIGH

Insertion of Sensitive Information Into Sent Data (CWE-201)

2025-12-05 security-advisories@github.com

GHSA-cmp6-m4wj-q63q

Information Disclosure Java Ubuntu Debian Red Hat Suse

8.2

CVSS 4.0 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

8.2 HIGH

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

Ubuntu

MEDIUM

qualitative

SUSE

HIGH

qualitative

Red Hat

7.5 HIGH

qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

EUVD ID Assigned

Mar 15, 2026 - 17:08 euvd

EUVD-2025-201456

Analysis Generated

Mar 15, 2026 - 17:08 vuln.today

CVE Published

Dec 05, 2025 - 18:15 nvd

HIGH 8.2

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

1,446 maven packages depend on at.yawk.lz4:lz4-java (99 direct, 1,354 indirect)
178 maven packages depend on org.lz4:lz4-java (57 direct, 123 indirect)

Ecosystem-wide dependent count for version 1.10.1 and other introduced versions.

DescriptionGitHub Advisory

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.

Analysis

Technical ContextAI

Information disclosure occurs when an application inadvertently reveals sensitive data to unauthorized actors through error messages, logs, or improper access controls.