---
id: CVE-2024-10549
aliases:
  - GHSA-wwr9-4gmr-xvq9
  - PYSEC-2026-1445
title: H2O Vulnerable to Denial of Service (DoS) via `/3/Parse` Endpoint
summary: H2O Vulnerable to Denial of Service (DoS) via `/3/Parse` Endpoint
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
vendor: h2o
product: h2o
ecosystem: pip
affected:
  - 'h2o >= 3.30.0.7, <= 3.46.0.1'
  - 'ai.h2o:h2o-core >= 3.30.0.7, <= 3.46.0.1'
published: '2025-03-20'
updated: '2026-07-07'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-wwr9-4gmr-xvq9'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2024-10549'
  - url: 'https://github.com/h2oai/h2o-3'
  - url: >-
      https://github.com/h2oai/h2o-3/blob/51c25940ded8b7d0acc8f3f72329fd9dedbb3a34/h2o-core/src/main/java/water/api/ParseHandler.java#L80
  - url: 'https://huntr.com/bounties/ce7bd2d6-fd38-440d-a91a-dd8f3fc06bc2'
tags:
  - osv
  - pip
epss: 0.00624
epssPercentile: 0.47709
ingestedAt: '2026-07-08T18:25:53.922Z'
---

## Overview

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.

## Affected packages

- `h2o >= 3.30.0.7, <= 3.46.0.1`
- `ai.h2o:h2o-core >= 3.30.0.7, <= 3.46.0.1`

## Remediation

Refer to the advisory for the patched release.