What’s Vulnerable › Vulnerabilities

CVE-2026-106452: yawkat LZ4 Java: LZ4BlockInputStream allocates an unvalidated compressed length from the stream header

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-06 · updated 2026-10-07
• Weakness: CWE-789

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.

Affected products

• yawkat lz4-java: before 1.11.2

References

• https://github.com/yawkat/lz4-java/commit/bb83dd16163cdb71231af06b0a5651881148a634
• https://github.com/yawkat/lz4-java/releases/tag/v1.11.2
• https://github.com/yawkat/lz4-java/security/advisories/GHSA-4v53-57pg-c464

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