CVE-2026-3960: H2o core H2O-3 Is Vulnerable To Code Vulnerability

MODERATE
Advisory Identifier: GHSA-qmcv-hh7c-3m56
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CVSS 5.9
CWE-94
Published
Advisory Summary

CVE-2026-3960 is a MODERATE (CVSS 5.9) h2o-3 is vulnerable to code vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting H2o core libraries in the Maven ecosystem. The issue involves h2o-3 is vulnerable to code injection. Remediation is available by upgrading affected packages to version 3.46.0.10.

CVE-2026-3960 at a Glance

CVE Identifier CVE-2026-3960
GHSA Identifier GHSA-qmcv-hh7c-3m56
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
Affected Product H2o core
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-3960

To remediate this vulnerability, upgrade all affected H2o core dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

ai.h2o:h2o-core fixed: 3.46.0.10 
<dependency>
    <groupId>ai.h2o</groupId>
    <artifactId>h2o-core</artifactId>
    <version>3.46.0.10</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=ai.h2o

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-3960, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=ai.h2o

Analyze the terminal output to locate any version of H2o core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.46.0.10), your application is affected.

Note: The mvn dependency:tree -Dincludes=ai.h2o command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. In H2o core, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-3960 Affected H2o core Versions

1 component(s)
Fixed Versions:
3.46.0.10
Product / Package Ecosystem Affected Versions Fixed Version
ai.h2o:h2o-core
maven/ai.h2o/h2o-core
Maven
< 3.46.0.10
3.46.0.10

References

NVD — CVE-2026-3960 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-3960
Security Fix Commit FIX COMMIT
https://github.com/h2oai/h2o-3/commit/b9ae2d3c5220db2dc53753357a783e590364d044
H2o core Source Repository REPOSITORY
https://github.com/h2oai/h2o-3
huntr.com/bounties/6954fe04-b... WEB
https://huntr.com/bounties/6954fe04-b905-453f-8c53-205ac8377e0d

Frequently Asked Questions

What is CVE-2026-3960?
CVE-2026-3960 is a security vulnerability in H2o core involving H2O-3 is Vulnerable to Code Injection under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which H2o core versions are affected?
Affected versions include releases prior to 3.46.0.10 across affected packages: ai.h2o:h2o-core.
What version fixes CVE-2026-3960?
Upgrading to 3.46.0.10 (or the latest patched release for your respective branch) resolves the vulnerability.
Is h2o-core affected?
Yes, ai.h2o:h2o-core is affected in releases prior to 3.46.0.10. Upgrade your dependency to 3.46.0.10 or later.
What is the CVSS score of CVE-2026-3960?
CVE-2026-3960 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-3960?
CVE-2026-3960 is classified under CWE-94: Improper Control of Generation of Code ('Code Injection') (The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.).
How can I check Maven dependencies for CVE-2026-3960?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=ai.h2o'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qmcv-hh7c-3m56",
  "modified" : "2026-05-04T20:15:45Z",
  "published" : "2026-04-23T12:31:34Z",
  "aliases" : [ "CVE-2026-3960" ],
  "summary" : "H2O-3 is Vulnerable to Code Injection",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "ai.h2o:h2o-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.46.0.10"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-3960"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/h2oai/h2o-3/commit/b9ae2d3c5220db2dc53753357a783e590364d044"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/h2oai/h2o-3"
  }, {
    "type" : "WEB",
    "url" : "https://huntr.com/bounties/6954fe04-b905-453f-8c53-205ac8377e0d"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-94" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-04T20:15:45Z",
    "nvd_published_at" : "2026-04-23T10:16:17Z"
  }
}