---
id: CVE-2026-69205
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,
  Ember’s HeaderP.parse uses a case-sensitive substring test for the
  Transfer-Encoding value and decodes header bytes with the platform default
  charset. Values …
severity: high
cvss: 8.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N'
cwe:
  - CWE-444
vendor: http4s
product: 'org.http4s:http4s-ember-core_3'
affected:
  - 'org.http4s:http4s-ember-core_3 <= 0.23.34'
  - 'org.http4s:http4s-ember-core_2.13 <= 0.23.34'
  - 'org.http4s:http4s-ember-core_2.12 <= 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:
  - 'org.http4s:http4s-ember-core_3 0.23.35'
  - 'org.http4s:http4s-ember-core_2.13 0.23.35'
  - 'org.http4s:http4s-ember-core_2.12 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: '2026-09-16'
sourceUpdated: '2026-09-16T20:38:04.943'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-69205'
references:
  - url: >-
      https://github.com/http4s/http4s/commit/5e88b2e7b4e6ea2f0c61040a4bc9de0d73e51217
    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-9998-894r-fwvr'
    label: security-advisories@github.com
  - url: 'https://github.com/advisories/GHSA-9998-894r-fwvr'
tags:
  - nvd
  - ghsa
  - maven
  - cve.org
aliases:
  - GHSA-9998-894r-fwvr
ecosystem: maven
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-15T19:32:59.406376Z'
ingestedAt: '2026-09-15T19:42:58.815Z'
epss: 0.00396
epssPercentile: 0.33523
---

## Overview

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HeaderP.parse uses a case-sensitive substring test for the Transfer-Encoding value and decodes header bytes with the platform default charset. Values such as Chunked are not recognized, values such as notchunked are incorrectly accepted, and Unicode case folding can turn a Kelvin-sign byte sequence into a match when UTF-8 is used. Intermediaries that apply RFC-compliant token and charset rules can therefore disagree with Ember’s Content-Length or zero-length framing, enabling TE.CL or TE.0 request smuggling, access-control bypass, cross-user request hijacking, and cache poisoning on the server path. Response smuggling through an ember-client gateway requires a malicious or compromised upstream. 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-2026-69205)

Affected packages:

- `org.http4s:http4s-ember-core_3 <= 0.23.34`
- `org.http4s:http4s-ember-core_2.13 <= 0.23.34`
- `org.http4s:http4s-ember-core_2.12 <= 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_3 0.23.35`
- `org.http4s:http4s-ember-core_2.13 0.23.35`
- `org.http4s:http4s-ember-core_2.12 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-9998-894r-fwvr