---
title: "CVE-2026-69202: Http4s - Denial of Service"
description: "Http4s prior to 0.23.35 and 1.0.0-M47 contains a denial of service caused by unbounded HTTP/2 flow-control window replenishment and unbounded per-stream data buffering, letting hostile peers exhaust heap memory, exploit requires HTTP/2 usage with ember-server or ember-client."
url: https://panop.io/threat-heartbeat/CVE-2026-69202/
---

# CVE-2026-69202 Http4s - Denial of Service

Http4s prior to 0.23.35 and 1.0.0-M47 contains a denial of service caused by unbounded HTTP/2 flow-control window replenishment and unbounded per-stream data buffering, letting hostile peers exhaust heap memory, exploit requires HTTP/2 usage with ember-server or ember-client.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.63% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-69202)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Published

15 September 2026

Updated

15 October 2026

Weakness

[CWE-400](https://cwe.mitre.org/data/definitions/400.html)

## Vendor fix

Update to version 0.23.35 or 1.0.0-M47 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-69202](https://nvd.nist.gov/vuln/detail/CVE-2026-69202)
- [https://github.com/http4s/http4s/commit/22d2335975d02dc9fb9fb75cfe002279521d86ac](https://github.com/http4s/http4s/commit/22d2335975d02dc9fb9fb75cfe002279521d86ac)
- [https://github.com/http4s/http4s/releases/tag/v0.23.35](https://github.com/http4s/http4s/releases/tag/v0.23.35)
- [https://github.com/http4s/http4s/releases/tag/v1.0.0-M47](https://github.com/http4s/http4s/releases/tag/v1.0.0-M47)
- [https://github.com/http4s/http4s/security/advisories/GHSA-6m4x-pp6q-5jmm](https://github.com/http4s/http4s/security/advisories/GHSA-6m4x-pp6q-5jmm)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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