# CVE-2024-10549: Denial of Service by ReDOS in h2oai/h2o-3

> An attacker can cause a denial of service in H2O-3 by sending simultaneous requests to the Parse endpoint, exhausting threads via ReDoS.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/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:** No
- **Published:** 20 Mar 2025
- **Updated:** 15 Oct 2025
- **Also known as:** GHSA-wwr9-4gmr-xvq9, PYSEC-2026-1445

## What is CVE-2024-10549?

CVE-2024-10549 is a high-severity denial of service vulnerability in h2oai/h2o-3, published on 20 Mar 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the `/3/Parse` endpoint of h2oai/h2o-3 version 3.46.0.1 allows for a denial of service (DoS) attack. The endpoint uses a user-specified string to construct a regular expression, which is then applied to another user-specified string. By sending multiple simultaneous requests, an attacker can exhaust all available threads, leading to a complete denial of service.

Weakness: CWE-1333 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2024-10549?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `h2o` | PyPI | From 3.30.0.7 to 3.46.0.1 | None |
| `h2o` | PyPI | From 3.30.0.7 to 3.46.0.1 | None |
| `h2o` | PyPI | From 3.30.0.7 to 3.46.0.1 | None |
| `ai.h2o:h2o-core` | Maven | From 3.30.0.7 to 3.46.0.1 | None |
| `ai.h2o:h2o-core` | Maven | From 3.30.0.7 to 3.46.0.1 | None |

Products: H2o H2o.

## How do I fix CVE-2024-10549?

No fix has been published for CVE-2024-10549 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-10549 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-10549 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-2024-10549 and fix it if it is affected.

What it is: CVE-2024-10549 is a high-severity denial of service vulnerability in h2oai/h2o-3, published on 20 Mar 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-2024-10549 exists.

Affected packages and fixed versions:
- h2o (PyPI): affected from 3.30.0.7 up to 3.46.0.1; no fix listed
- h2o (PyPI): affected from 3.30.0.7 up to 3.46.0.1; no fix listed
- h2o (PyPI): affected from 3.30.0.7 up to 3.46.0.1; no fix listed
- ai.h2o:h2o-core (Maven): affected from 3.30.0.7 up to 3.46.0.1; no fix listed
- ai.h2o:h2o-core (Maven): affected from 3.30.0.7 up to 3.46.0.1; no fix listed

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-2024-10549/ (Markdown: https://insights.sbomify.com/CVE-2024-10549/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-10549
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-10549
- OSV: https://osv.dev/vulnerability/CVE-2024-10549

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-10549/
Summaries are generated and may contain mistakes; the official description above is the record.