CVE-2025-66566

HIGHPre-NVD 8.28.2—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6%, top 53% 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, secondary
8.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 8.2Exploit: None knownExposed services: Not assessed

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
8.2HIGHmedium confidence
EG Risk
52
EG Risk 52/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity82% × 45%
Exploitation1% × 40%
Automatability100% × 15%
EPSS PROB
0.6%
EPSS %ILE
47th
KEV
Not listed

Published

December 5, 2025

Last Modified

September 25, 2026

Advisory Details (2)

Auto-updated Aug 8, 2026
Patch available. Sources: github_commit, github.
githubMentions a patch (unverified)

Java-based decompressor implementations can leak information from uninitialized output buffer · Advisory · yawkat/lz4-java · GitHub

https://github.com/yawkat/lz4-java/security/advisories/GHSA-cmp6-m4wj-q63q
github_commit Patch Available

commit 33d180cb70c4 (yawkat/lz4-java)

Patch available: yawkat/lz4-java v1.10.1 (contains commit 33d180cb70c4)

https://github.com/yawkat/lz4-java/commit/33d180cb70c4d93c80fb0dc3ab3002f457e93840

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(9)

Vendor / EcosystemFix (by version range) / 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.el9eap2026-02-04redhat
redhatpatch2026-02-04redhat
redhateap8-wildfly-0:8.1.4-2.GA_redhat_00005.1.el8eap2026-02-04redhat
redhatjmc-0:8.2.0-17.el9_4.22026-02-03redhat
redhatjmc-0:8.2.0-18.el9_7.22026-01-19redhat
redhatjmc-0:8.2.0-18.el9_6.22026-01-19redhat
redhatcryostat/jfr-datasource-rhel9:4.1.0-162026-01-19redhat

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

(8 across 5 ecosystems)
Maven(4)
PackageVulnerable rangeFix by version rangeDependents
at.yawk.lz4:lz4-java1.10.0, 1.8.1, 1.9.0
  • every version up to 1.10.1: fixed in 1.10.1
—
net.jpountz.lz4:lz41.0.0 ... 1.3.0 (7 versions)
  • every version through 1.8.1: no fix on record
—
org.lz4:lz4-java1.4 ... 1.8.1 (10 versions)
  • every version through 1.8.1: no fix on record
—
org.lz4:lz4-pure-java1.7.0, 1.8.0
  • every version through 1.8.1: no fix on record
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
lz4-java1.5.1-3, 1.8.0-1, 1.8.0-2, 1.8.0-3, 1.8.0-4
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
lz4-java1.11.2+ds1-1, 1.11.2+ds1-2, 1.11.2+ds1-3, 1.8.0-3, 1.8.0-4
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
lz4-java1.11.2+ds1-1, 1.11.2+ds1-2, 1.11.2+ds1-3, 1.8.0-4
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
lz4-java1.8.0-4
  • every version up to 1.11.2+ds1-1: fixed in 1.11.2+ds1-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 30× 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 204 total refreshes for this CVE.

  1. 2026-10-10 19:59 UTCEPSS rescore
  2. 2026-10-09 20:06 UTCEPSS rescore
  3. 2026-10-08 17:11 UTCEPSS rescore
  4. 2026-10-07 23:47 UTCEPSS rescore
  5. 2026-10-06 15:17 UTCEPSS rescore
  6. 2026-10-05 17:42 UTCEPSS rescore
  7. 2026-10-04 23:21 UTCEPSS rescore
  8. 2026-10-03 14:25 UTCEPSS rescore
  9. 2026-10-01 19:49 UTCEPSS rescore
  10. 2026-09-30 15:02 UTCEPSS rescore
  11. 2026-09-29 15:20 UTCEPSS rescore
  12. 2026-09-28 13:50 UTCEPSS rescore
  13. 2026-09-28 13:50 UTCEPSS rescore
  14. 2026-09-26 15:58 UTCEPSS rescore
  15. 2026-09-26 15:58 UTCEPSS rescore
  16. 2026-09-25 23:28 UTCEG score recompute
  17. 2026-09-25 23:28 UTCVendor advisory
  18. 2026-09-24 14:02 UTCEPSS rescore
  19. 2026-09-23 13:47 UTCEPSS rescore
  20. 2026-09-20 20:15 UTCEPSS rescore
  21. 2026-09-19 15:42 UTCEPSS rescore
  22. 2026-09-18 19:27 UTCEPSS rescore
  23. 2026-09-17 19:30 UTCEPSS rescore
  24. 2026-09-16 14:07 UTCEPSS rescore
  25. 2026-09-15 03:10 UTCEPSS rescore
Show 75 more
  1. 2026-09-13 16:46 UTCEPSS rescore
  2. 2026-09-12 15:00 UTCEPSS rescore
  3. 2026-09-12 07:40 UTCOSV refresh
  4. 2026-09-11 14:52 UTCEPSS rescore
  5. 2026-09-11 09:36 UTCEPSS rescore
  6. 2026-09-10 09:34 UTCEPSS rescore
  7. 2026-09-08 22:00 UTCEPSS rescore
  8. 2026-09-07 16:00 UTCEPSS rescore
  9. 2026-09-06 13:47 UTCEPSS rescore
  10. 2026-09-04 05:06 UTCEPSS rescore
  11. 2026-09-02 14:11 UTCEPSS rescore
  12. 2026-09-01 13:53 UTCEPSS rescore
  13. 2026-08-30 19:16 UTCEPSS rescore
  14. 2026-08-30 01:21 UTCEPSS rescore
  15. 2026-08-28 21:40 UTCEPSS rescore
  16. 2026-08-27 14:24 UTCEPSS rescore
  17. 2026-08-26 14:45 UTCEPSS rescore
  18. 2026-08-25 13:48 UTCEPSS rescore
  19. 2026-08-24 14:16 UTCEPSS rescore
  20. 2026-08-24 13:02 UTCOSV refresh
  21. 2026-08-23 00:18 UTCEPSS rescore
  22. 2026-08-21 23:48 UTCEPSS rescore
  23. 2026-08-20 22:55 UTCEPSS rescore
  24. 2026-08-19 17:03 UTCEPSS rescore
  25. 2026-08-18 13:47 UTCEPSS rescore
  26. 2026-08-17 13:46 UTCEPSS rescore
  27. 2026-08-16 14:55 UTCEPSS rescore
  28. 2026-08-16 02:13 UTCEPSS rescore
  29. 2026-08-15 01:30 UTCEPSS rescore
  30. 2026-08-15 01:29 UTCEPSS rescore
  31. 2026-08-13 21:59 UTCEPSS rescore
  32. 2026-08-12 13:50 UTCEPSS rescore
  33. 2026-08-11 13:42 UTCEPSS rescore
  34. 2026-08-10 23:59 UTCEPSS rescore
  35. 2026-08-09 13:46 UTCEPSS rescore
  36. 2026-08-09 13:46 UTCEPSS rescore
  37. 2026-08-08 16:36 UTCEPSS rescore
  38. 2026-08-08 08:29 UTCEG score recompute
  39. 2026-08-08 08:29 UTCVendor advisory
  40. 2026-08-07 16:26 UTCEPSS rescore
  41. 2026-08-06 13:46 UTCEPSS rescore
  42. 2026-08-05 19:17 UTCEPSS rescore
  43. 2026-08-05 19:17 UTCEPSS rescore
  44. 2026-08-04 15:09 UTCEPSS rescore
  45. 2026-08-04 10:37 UTCEPSS rescore
  46. 2026-08-03 10:35 UTCEPSS rescore
  47. 2026-08-02 02:26 UTCEPSS rescore
  48. 2026-08-01 04:15 UTCEPSS rescore
  49. 2026-07-31 22:12 UTCOSV refresh
  50. 2026-07-30 16:27 UTCEPSS rescore
  51. 2026-07-30 01:30 UTCEPSS rescore
  52. 2026-07-28 15:35 UTCEPSS rescore
  53. 2026-07-27 14:12 UTCEPSS rescore
  54. 2026-07-26 14:54 UTCEPSS rescore
  55. 2026-07-26 14:54 UTCEPSS rescore
  56. 2026-07-25 14:17 UTCEPSS rescore
  57. 2026-07-24 14:17 UTCEPSS rescore
  58. 2026-07-24 14:17 UTCEPSS rescore
  59. 2026-07-23 14:18 UTCEPSS rescore
  60. 2026-07-23 14:18 UTCEPSS rescore
  61. 2026-07-23 03:01 UTCEG score recompute
  62. 2026-07-22 14:08 UTCEPSS rescore
  63. 2026-07-21 15:24 UTCEPSS rescore
  64. 2026-07-20 17:08 UTCEPSS rescore
  65. 2026-07-19 14:30 UTCEPSS rescore
  66. 2026-07-19 14:30 UTCEPSS rescore
  67. 2026-07-19 02:28 UTCEPSS rescore
  68. 2026-07-18 10:04 UTCEPSS rescore
  69. 2026-07-18 10:04 UTCEPSS rescore
  70. 2026-07-16 17:02 UTCEPSS rescore
  71. 2026-07-15 16:57 UTCEPSS rescore
  72. 2026-07-15 16:57 UTCEPSS rescore
  73. 2026-07-15 01:59 UTCEPSS rescore
  74. 2026-07-15 01:59 UTCEPSS rescore
  75. 2026-07-14 05:25 UTCOSV refresh

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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 on December 5, 2025, with the most recent update on September 25, 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 0.6% probability of exploitation in the next 30 days (47th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2025-66566?
CVE-2025-66566 has a CVSS base score of 8.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2025-66566?
A fix for CVE-2025-66566 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2025-66566 are linked in the Vendor Advisories panel on this page.

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