CVE-2025-6544

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2025-09-22. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

A deserialization vulnerability exists in h2oai/h2o-3 versions <= 3.46.0.8, allowing attackers to read arbitrary system files and execute arbitrary code. The vulnerability arises from improper handling of JDBC connection parameters, which can be exploited by bypassing regular expression checks and using double URL encoding. This issue impacts all users of the affected versions.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
54.2%
KEV
Not listed

Published

September 21, 2025

Last Modified

June 17, 2026

Advisory Details (2)

Auto-updated Jul 14, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

huntr - The world's first bug bounty platform for AI/ML

https://huntr.com/bounties/53f35a0f-d644-4f82-93aa-89fe7e0aed40
github_commit

commit 0298ee348f5c (h2oai/h2o-3)

Fix landed in h2oai/h2o-3 commit 0298ee348f5c — awaiting tagged release

https://github.com/h2oai/h2o-3/commit/0298ee348f5c73673b7b542158081e79605f5f25

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
mavenai.h2o:h2o-core—ghsa
piph2o—ghsa

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

(2 across 2 ecosystems)
Maven(1)
PackageVulnerable rangeFixed inDependents
ai.h2o:h2o-core0.1.10 ... 3.8.3.4 (253 versions)——
PyPI(1)
PackageVulnerable rangeFixed inDependents
h2o3.10.0.10 ... 3.46.0.7 (118 versions)——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 43× 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.

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

Frequently asked(5)

What is CVE-2025-6544?
CVE-2025-6544 is a critical vulnerability published on September 21, 2025. A deserialization vulnerability exists in h2oai/h2o-3 versions <= 3.46.0.8, allowing attackers to read arbitrary system files and execute arbitrary code. The vulnerability arises from improper handling of JDBC connection parameters, which can be exploited by bypassing regular expression checks and…
When was CVE-2025-6544 disclosed?
CVE-2025-6544 was first published in the National Vulnerability Database on September 21, 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-2025-6544 actively exploited?
CVE-2025-6544 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 54.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-6544?
CVE-2025-6544 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2025-6544?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-6544, 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.

Dependency Blast Radius

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