CVE-2025-6544 — Vulnerability in ai.h2o:h2o-core — CVE Details

CRITICAL

H2O affected by a deserialization vulnerability

Published September 22, 2025Updated June 29, 2026Source: osv

Summary

A deserialization vulnerability exists in h2oai/h2o-3 versions <= 3.46.0.7, 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.

Advisory Timeline

First published September 22, 2025 (385 days ago).
Last revised June 29, 2026 — 280 days after initial publication.

Affected Packages (2)

Affects 2 ecosystems: maven (1), pypi (1).

Package	Ecosystem	Affected	Fixed In
ai.h2o:h2o-core	maven	0.1.10, 0.1.11, 0.1.12, 0.1.13 (+249 more)	Range-based data available
h2o	pypi	3.10.0.10, 3.10.0.3, 3.10.0.6, 3.10.0.7 (+114 more)	Range-based data available

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CWE-502
Deserialization of Untrusted DataMITRE

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

References

Frequently Asked Questions

What is CVE-2025-6544?: H2O affected by a deserialization vulnerability 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-2025-6544?: CVE-2025-6544 affects ai.h2o:h2o-core and h2o. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2025-6544 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score

9.8

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

GHSA-5w3j-gwgh-4rfv

PYSEC-2026-349

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