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Vulnerability · Published Oct 6, 2026 · Assigned by GitHub_M

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

Medium 5.3

In plain English

A medium-severity security flaw in lz4-java from yawkat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.5%top 60.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12lz4-javano fix listedDEBIAN-CVE-2026-106452
Debian:13lz4-javano fix listedDEBIAN-CVE-2026-106452
Debian:14lz4-java1.11.2+ds1-1DEBIAN-CVE-2026-106452
Mavenat.yawk.lz4:lz4-java1.11.2GHSA-4v53-57pg-c464
Mavenorg.lz4:lz4-javano fix listedGHSA-4v53-57pg-c464
Ubuntu:22.04:LTSlz4-javano fix listedUBUNTU-CVE-2026-106452
Ubuntu:24.04:LTSlz4-javano fix listedUBUNTU-CVE-2026-106452
Ubuntu:26.04:LTSlz4-javano fix listedUBUNTU-CVE-2026-106452
Ubuntu:26.10lz4-javano fix listedUBUNTU-CVE-2026-106452

Affected products (as reported)

VendorProductVersions
yawkat lz4-java < 1.11.2

Weakness: CWE-789 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References