CVE-2026-59949Network attack vector

JVM crash via unchecked XXHash JNI ranges

Published Aug 18, 2026 · Updated Aug 18, 2026

Denial of service in yawkat lz4-java before 1.11.1 allows attackers to crash the JVM via invalid JNI XXHash arguments. StreamingXXHash32JNI.update and StreamingXXHash64JNI.update passed caller-controlled byte arrays and off/len values into XXHashJNI without range validation, and SafeUtils.checkRange skipped a null-array check when len was 0, letting null arrays or oversized ranges cross the JNI boundary. Exposure requires attacker influence over the array reference or its bounds rather than only byte contents; reachable cases terminate the JVM, and oversized ranges can read past the Java array before the crash.

CVSS severity6.5
Medium
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in yawkat lz4-java before 1.11.1 allows attackers to crash the JVM via invalid JNI XXHash arguments. StreamingXXHash32JNI.update and StreamingXXHash64JNI.update passed caller-controlled byte arrays and off/len values into XXHashJNI without range validation, and SafeUtils.checkRange skipped a null-array check when len was 0, letting null arrays or oversized ranges cross the JNI boundary. Exposure requires attacker influence over the array reference or its bounds rather than only byte contents; reachable cases terminate the JVM, and oversized ranges can read past the Java array before the crash.

The record

CVE
CVE-2026-59949
Published
Aug 18, 2026
Updated
Aug 18, 2026
Vendor
yawkat
Product
lz4-java
Classifications
CWE-125, CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.11.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

yawkat · lz4-javaversion=< 1.11.1

Published CVSS scores

6.5GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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