---
id: CVE-2026-69218
title: Http4s is a Scala interface for HTTP services
summary: >-
  Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47,
  When Ember receives an HTTP/2 HEADERS or PUSH_PROMISE frame without
  END_HEADERS, H2Connection buffers the header block and subsequent CONTINUATION
  fragments w…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-770
vendor: http4s
product: http4s
affected:
  - http4s < 0.23.35
  - 'http4s >= 1.0.0-M1, < 1.0.0-M47'
patched:
  - 'org.http4s:http4s-ember-core_2.12 0.23.35'
  - 'org.http4s:http4s-ember-core_2.13 0.23.35'
  - 'org.http4s:http4s-ember-core_3 0.23.35'
  - 'org.http4s:http4s-ember-core_2.13 1.0.0-M47'
  - 'org.http4s:http4s-ember-core_3 1.0.0-M47'
published: '2026-09-15'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T17:16:46.710'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-69218'
references:
  - url: >-
      https://github.com/http4s/http4s/commit/6e8eccd64a6a74ab4811897881e95e0e1b3a818e
    label: security-advisories@github.com
  - url: >-
      https://github.com/http4s/http4s/commit/f9dcca4f5a17992ac0972fafd7920f9bc12cdc51
    label: security-advisories@github.com
  - url: 'https://github.com/http4s/http4s/releases/tag/v0.23.35'
    label: security-advisories@github.com
  - url: 'https://github.com/http4s/http4s/releases/tag/v1.0.0-M47'
    label: security-advisories@github.com
  - url: 'https://github.com/http4s/http4s/security/advisories/GHSA-cp4q-fqw9-4hf6'
    label: security-advisories@github.com
  - url: 'https://github.com/advisories/GHSA-cp4q-fqw9-4hf6'
tags:
  - nvd
  - cve.org
  - ghsa
  - maven
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-17T16:46:52.034934Z'
epss: 0.0046
epssPercentile: 0.39052
aliases:
  - GHSA-cp4q-fqw9-4hf6
ecosystem: maven
ingestedAt: '2026-09-15T19:42:58.832Z'
---

## Overview

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, When Ember receives an HTTP/2 HEADERS or PUSH_PROMISE frame without END_HEADERS, H2Connection buffers the header block and subsequent CONTINUATION fragments without a size bound. A remote peer can keep an incomplete block open and exhaust heap memory before request decoding, affecting an ember-server or ember-client configured with withHttp2. The remediation tracks accumulated size against SETTINGS_MAX_HEADER_LIST_SIZE derived from EmberServerBuilder.maxHeaderSize or EmberClientBuilder.maxResponseHeaderSize, sends GOAWAY when the limit is exceeded, and applies receiveHeadersTimeout to incomplete blocks. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-69218)

Affected packages:

- `org.http4s:http4s-ember-core_2.12 <= 0.23.34`
- `org.http4s:http4s-ember-core_2.13 <= 0.23.34`
- `org.http4s:http4s-ember-core_3 <= 0.23.34`
- `org.http4s:http4s-ember-core_2.13 >= 1.0.0-M1, <= 1.0.0-M46`
- `org.http4s:http4s-ember-core_3 >= 1.0.0-M1, <= 1.0.0-M46`

Patched in:

- `org.http4s:http4s-ember-core_2.12 0.23.35`
- `org.http4s:http4s-ember-core_2.13 0.23.35`
- `org.http4s:http4s-ember-core_3 0.23.35`
- `org.http4s:http4s-ember-core_2.13 1.0.0-M47`
- `org.http4s:http4s-ember-core_3 1.0.0-M47`

Source: https://github.com/advisories/GHSA-cp4q-fqw9-4hf6