# CVE-2026-3960: Remote Code Execution in h2oai/h2o-3

> Unauthenticated attackers can execute arbitrary code on H2O-3 servers by bypassing JDBC parameter blacklists via PostgreSQL driver exploitation.

- **Severity:** Medium 5.9 (`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Apr 2026
- **Updated:** 23 Apr 2026
- **Also known as:** GHSA-qmcv-hh7c-3m56, PYSEC-2026-2180

## What is CVE-2026-3960?

CVE-2026-3960 is a medium-severity code injection vulnerability in h2oai/h2o-3, published on 23 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2026-3960?

3 open source packages ship an affected version, including ai.h2o:h2o-core and h2o. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ai.h2o:h2o-core` | Maven | All versions | 3.46.0.10 |
| `ai.h2o:h2o-core` | Maven | All versions | 3.46.0.10 |
| `h2o` | PyPI | All versions | 3.46.0.10 |

Products: H2o H2o.

## How do I fix CVE-2026-3960?

Upgrade ai.h2o:h2o-core to 3.46.0.10 or later.

## Is CVE-2026-3960 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3960 exists.

## Other vulnerabilities in h2oai/h2o-3

- [CVE-2023-6016](https://insights.sbomify.com/CVE-2023-6016/): H2O Remote Code Execution via POJO Model Import (critical 10.0)
- [CVE-2025-6544](https://insights.sbomify.com/CVE-2025-6544/): Deserialization Vulnerability in h2oai/h2o-3 (critical 9.8)
- [CVE-2024-10553](https://insights.sbomify.com/CVE-2024-10553/): Jdbc Deserialization in h2oai/h2o-3 (critical 9.8)
- [CVE-2023-6569](https://insights.sbomify.com/CVE-2023-6569/): External Control of File Name or Path in h2oai/h2o-3 (critical 9.3)
- [CVE-2023-6013](https://insights.sbomify.com/CVE-2023-6013/): H2O Local File Include (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3960 and fix it if it is affected.

What it is: CVE-2026-3960 is a medium-severity code injection vulnerability in h2oai/h2o-3, published on 23 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3960 exists.

Affected packages and fixed versions:
- ai.h2o:h2o-core (Maven): affected all versions; fixed in 3.46.0.10
- ai.h2o:h2o-core (Maven): affected all versions; fixed in 3.46.0.10
- h2o (PyPI): affected all versions; fixed in 3.46.0.10

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-3960/ (Markdown: https://insights.sbomify.com/CVE-2026-3960/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3960
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3960
- OSV: https://osv.dev/vulnerability/CVE-2026-3960

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3960/
Summaries are generated and may contain mistakes; the official description above is the record.