CVE-2025-66566

HIGHPre-NVD 8.28.2—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.2 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 79% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
8.2
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 8.2Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
8.2
EG Score
8.2(medium)
EPSS
42.8%
KEV
Not listed

Published

December 5, 2025

Last Modified

June 17, 2026

References (2)

Vendor Advisories for CVE-2025-66566(15)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(10)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatjmc-0:8.2.0-19.el9_8.22026-05-26redhat
redhatlz4-java2026-03-05redhat
redhateap8-wildfly-0:8.1.4-2.GA_redhat_00005.1.el8eap2026-02-04redhat
redhatpatch2026-02-04redhat
redhateap8-wildfly-0:8.1.4-2.GA_redhat_00005.1.el9eap2026-02-04redhat
redhatjmc-0:8.2.0-17.el9_4.22026-02-03redhat
redhatcryostat/jfr-datasource-rhel9:4.1.0-162026-01-19redhat
redhatjmc-0:8.2.0-18.el9_7.22026-01-19redhat
redhatjmc-0:8.2.0-18.el9_6.22026-01-19redhat
redhatpatch2026-01-15redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 1 ecosystem)
Maven(4)
PackageVulnerable rangeFixed inDependents
at.yawk.lz4:lz4-java1.10.0, 1.8.1, 1.9.01.10.1—
net.jpountz.lz4:lz41.0.0 ... 1.3.0 (7 versions)——
org.lz4:lz4-java1.4 ... 1.8.1 (10 versions)——
org.lz4:lz4-pure-java1.7.0, 1.8.0——

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 101 total refreshes for this CVE.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-09 19:09 UTCEPSS rescore
  3. 2026-07-08 15:15 UTCEPSS rescore
  4. 2026-07-07 13:46 UTCEPSS rescore
  5. 2026-07-06 16:27 UTCEPSS rescore
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  7. 2026-07-06 02:23 UTCEPSS rescore
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  9. 2026-07-05 02:30 UTCEPSS rescore
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  11. 2026-07-04 06:31 UTCEPSS rescore
  12. 2026-07-04 06:30 UTCEPSS rescore
  13. 2026-07-01 15:06 UTCEPSS rescore
  14. 2026-07-01 15:06 UTCEPSS rescore
  15. 2026-06-30 23:22 UTCEPSS rescore
  16. 2026-06-29 14:06 UTCEPSS rescore
  17. 2026-06-29 14:06 UTCEPSS rescore
  18. 2026-06-28 14:07 UTCEPSS rescore
  19. 2026-06-28 14:07 UTCEPSS rescore
  20. 2026-06-28 04:56 UTCEPSS rescore
  21. 2026-06-28 04:55 UTCEPSS rescore
  22. 2026-06-27 03:08 UTCEPSS rescore
  23. 2026-06-26 02:46 UTCOSV refresh
  24. 2026-06-25 13:49 UTCEPSS rescore
  25. 2026-06-24 14:04 UTCEPSS rescore
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  1. 2026-06-24 14:04 UTCEPSS rescore
  2. 2026-06-23 21:32 UTCEPSS rescore
  3. 2026-06-23 21:32 UTCEPSS rescore
  4. 2026-06-22 14:25 UTCEPSS rescore
  5. 2026-06-21 14:56 UTCEPSS rescore
  6. 2026-06-21 14:56 UTCEPSS rescore
  7. 2026-06-21 01:59 UTCEPSS rescore
  8. 2026-06-21 01:59 UTCEPSS rescore
  9. 2026-06-19 19:25 UTCEPSS rescore
  10. 2026-06-19 19:25 UTCEPSS rescore
  11. 2026-06-18 17:52 UTCEPSS rescore
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  13. 2026-06-17 17:52 UTCEPSS rescore
  14. 2026-06-16 17:52 UTCEPSS rescore
  15. 2026-06-15 17:48 UTCEPSS rescore
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  17. 2026-06-14 23:18 UTCEPSS rescore
  18. 2026-06-13 23:00 UTCEPSS rescore
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  20. 2026-06-12 23:11 UTCEPSS rescore
  21. 2026-06-11 14:00 UTCEPSS rescore
  22. 2026-06-10 22:18 UTCEPSS rescore
  23. 2026-06-10 22:18 UTCEPSS rescore
  24. 2026-06-10 13:22 UTCEPSS rescore
  25. 2026-06-08 15:14 UTCEG score recompute▲ 8.20
  26. 2026-06-08 15:14 UTCVendor advisory
  27. 2026-06-08 14:17 UTCEPSS rescore
  28. 2026-06-08 14:16 UTCEPSS rescore
  29. 2026-06-07 15:24 UTCEPSS rescore
  30. 2026-06-07 15:24 UTCEPSS rescore
  31. 2026-06-06 13:47 UTCEPSS rescore
  32. 2026-06-06 13:47 UTCEPSS rescore
  33. 2026-06-05 22:46 UTCEPSS rescore
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  35. 2026-06-05 06:10 UTCEPSS rescore
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  37. 2026-06-04 13:12 UTCEPSS rescore
  38. 2026-06-04 13:12 UTCEPSS rescore
  39. 2026-06-02 20:13 UTCEPSS rescore
  40. 2026-06-02 20:12 UTCEPSS rescore
  41. 2026-06-02 03:09 UTCOSV refresh
  42. 2026-06-01 13:51 UTCEPSS rescore
  43. 2026-06-01 13:51 UTCEPSS rescore
  44. 2026-05-31 22:30 UTCEPSS rescore
  45. 2026-05-31 22:30 UTCEPSS rescore
  46. 2026-05-31 00:16 UTCEPSS rescore
  47. 2026-05-31 00:16 UTCEPSS rescore
  48. 2026-05-29 13:44 UTCEPSS rescore
  49. 2026-05-28 13:44 UTCEPSS rescore
  50. 2026-05-28 13:44 UTCEPSS rescore
  51. 2026-05-28 13:44 UTCEPSS rescore
  52. 2026-05-27 13:40 UTCEPSS rescore
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  56. 2026-05-26 13:44 UTCEPSS rescore
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  59. 2026-05-26 07:18 UTCEPSS rescore
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  62. 2026-05-23 15:21 UTCEPSS rescore
  63. 2026-05-22 21:16 UTCEPSS rescore
  64. 2026-05-22 21:16 UTCEPSS rescore
  65. 2026-05-21 22:43 UTCEPSS rescore
  66. 2026-05-21 03:56 UTCEG score recompute
  67. 2026-05-21 03:56 UTCVendor advisory
  68. 2026-05-20 22:37 UTCEPSS rescore
  69. 2026-05-20 22:37 UTCEPSS rescore
  70. 2026-05-20 22:37 UTCEPSS rescore
  71. 2026-05-20 22:37 UTCEPSS rescore
  72. 2026-05-20 11:21 UTCEPSS rescore
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  74. 2026-05-20 11:21 UTCEPSS rescore
  75. 2026-05-20 11:21 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2025-66566?
CVE-2025-66566 is a high vulnerability published on December 5, 2025. 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…
When was CVE-2025-66566 disclosed?
CVE-2025-66566 was first published in the National Vulnerability Database on December 5, 2025, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-66566 actively exploited?
CVE-2025-66566 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 42.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-66566?
CVE-2025-66566 has a CVSS v3 base score of 8.2 (NVD).
How do I remediate CVE-2025-66566?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-66566, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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