Remote Code Execution in h2oai/h2o-3

published 2026-04-23 6 mo ago modified 2026-10-26 13 d ago also GHSA-qmcv-hh7c-3m56 , PYSEC-2026-2180 , EUVD-2026-25205

cvss: 5.9; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 61%
public exploits: 0; none known

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.

Patch / fix

fixed in 3 links 1

maven ai.h2o:h2o-core 3.46.0.10
pypi h2o 3.46.0.10
h2oai h2oai/h2o-3 3.46.0.10

github.com/h2oai/h2o-3@b9ae2d3 commit

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 6 mo ago (2026-04-23)

Exploit prediction

0.94% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

huntr.com https://huntr.com/bounties/6954fe04-b905-453f-8c53-205ac8377e0d referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.0	5.9	CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
OSV	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub	3.0	5.9	CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem	package	affected	fixed in
maven	ai.h2o:h2o-core	<3.46.0.10	3.46.0.10
pypi	h2o	<3.46.0.10	3.46.0.10

Affected products

h2oai h2oai/h2o-3

Classification

Weakness

CWE-94 Improper Control of Generation of Code

References

github.com /h2oai/h2o-3/commit/b9ae2d3c5220db2dc53753357a783e590364d044
web, patch
huntr.com /bounties/6954fe04-b905-453f-8c53-205ac8377e0d
web, exploit, third-party-advisory, evidence
nvd.nist.gov /vuln/detail/CVE-2026-3960
advisory
github.com /h2oai/h2o-3
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary