# CVE-2025-6507: Deserialization of Untrusted Data in h2oai/h2o-3

> Attackers can bypass JDBC parameter filters to trigger deserialization, leading to arbitrary code execution and system file access in H2O-3.

- **Severity:** Critical 9.8 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Sep 2025
- **Updated:** 2 Sep 2025

## What is CVE-2025-6507?

CVE-2025-6507 is a critical unsafe deserialization vulnerability in h2oai/h2o-3, published on 1 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the h2oai/h2o-3 repository allows attackers to exploit deserialization of untrusted data, potentially leading to arbitrary code execution and reading of system files. This issue affects the latest master branch version 3.47.0.99999. The vulnerability arises from the ability to bypass regular expression filters intended to prevent malicious parameter injection in JDBC connections. Attackers can manipulate spaces between parameters to evade detection, allowing for unauthorized file access and code execution. The vulnerability is addressed in version 3.46.0.8.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2025-6507?


## How do I fix CVE-2025-6507?

No fix has been published for CVE-2025-6507 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-6507 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-6507 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-6507 and fix it if it is affected.

What it is: CVE-2025-6507 is a critical unsafe deserialization vulnerability in h2oai/h2o-3, published on 1 Sep 2025. 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-2025-6507 exists.

Affected product: h2oai/h2o-3. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2025-6507/ (Markdown: https://insights.sbomify.com/CVE-2025-6507/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-6507
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-6507
- OSV: https://osv.dev/vulnerability/CVE-2025-6507

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-6507/
Summaries are generated and may contain mistakes; the official description above is the record.