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CVE-2026-3960 — Vulnerability in h2o — CVE Details

CRITICAL

Published April 23, 2026Updated July 13, 2026Source: osv

Summary

A critical remote code execution vulnerability exists in the unauthenticated REST API endpoint /99/ImportSQLTable in H2O-3 version 3.46.0.9 and prior. The vulnerability arises due to insufficient security controls in the parameter blacklist mechanism, which only targets MySQL JDBC driver-specific dangerous parameters. An attacker can bypass these controls by switching the JDBC URL protocol to jdbc:postgresql: and exploiting PostgreSQL JDBC driver-specific parameters such as socketFactory and socketFactoryArg. This allows unauthenticated attackers to execute arbitrary code on the H2O-3 server with the privileges of the H2O-3 process. The issue is resolved in version 3.46.0.10.

Advisory Timeline

  • First published April 23, 2026 (172 days ago).
  • Last revised July 13, 2026 — 81 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

pip
Update h2o to 3.46.0.10 or later
pip install "h2o>=3.46.0.10"

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (1)

Affects 1 ecosystem: pypi (1).

PackageEcosystemAffectedFixed In
h2o
pypi
3.10.0.10, 3.10.0.3, 3.10.0.6, 3.10.0.7 (+116 more)3.46.0.10

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 9.8 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

References

Frequently Asked Questions

What is CVE-2026-3960?
This vulnerability has been assigned a severity rating of CRITICAL (CVSS score: 9.8/10).
How do I check if my project is affected by CVE-2026-3960?
CVE-2026-3960 affects h2o. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-3960 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
9.8

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

PYSEC-2026-2180
GHSA-qmcv-hh7c-3m56

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