---
title: "CVE-2026-69218: Http4s - Denial of Service"
description: "Http4s prior to 0.23.35 and 1.0.0-M47 contains a denial of service caused by unbounded buffering of HTTP/2 header blocks in H2Connection, letting remote attackers exhaust heap memory, exploit requires sending incomplete header blocks."
url: https://panop.io/threat-heartbeat/CVE-2026-69218/
---

# CVE-2026-69218 Http4s - Denial of Service

Http4s prior to 0.23.35 and 1.0.0-M47 contains a denial of service caused by unbounded buffering of HTTP/2 header blocks in H2Connection, letting remote attackers exhaust heap memory, exploit requires sending incomplete header blocks.

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-2026-69218)

## 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-770](https://cwe.mitre.org/data/definitions/770.html)

## Vendor fix

Upgrade to versions 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-2026-69218](https://nvd.nist.gov/vuln/detail/CVE-2026-69218)
- [https://github.com/http4s/http4s/commit/f9dcca4f5a17992ac0972fafd7920f9bc12cdc51](https://github.com/http4s/http4s/commit/f9dcca4f5a17992ac0972fafd7920f9bc12cdc51)
- [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-cp4q-fqw9-4hf6](https://github.com/http4s/http4s/security/advisories/GHSA-cp4q-fqw9-4hf6)
- [https://github.com/http4s/http4s/commit/6e8eccd64a6a74ab4811897881e95e0e1b3a818e](https://github.com/http4s/http4s/commit/6e8eccd64a6a74ab4811897881e95e0e1b3a818e)

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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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