---
id: CVE-2026-69210
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,
  WebSocket FrameTranscoder.bodyLength rejects extended payload lengths above
  Integer.MAX_VALUE but permits negative 64-bit lengths. A remote client that
  comple…
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-835
  - CWE-1284
vendor: http4s
product: http4s
affected:
  - http4s < 0.23.35
  - 'http4s >= 1.0.0-M1, < 1.0.0-M47'
published: '2026-09-15'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T17:16:46.500'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-69210'
references:
  - url: >-
      https://github.com/http4s/http4s/commit/c7d3ef90dc2ed1cd464968ab1b34f2f1762ddae2
    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-3j86-pj9g-jchr'
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-17T16:45:07.781762Z'
epss: 0.0063
epssPercentile: 0.47884
ingestedAt: '2026-09-15T19:42:58.833Z'
---

## Overview

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, WebSocket FrameTranscoder.bodyLength rejects extended payload lengths above Integer.MAX_VALUE but permits negative 64-bit lengths. A remote client that completes a WebSocket handshake through an Ember server can send such a frame, causing the decoder to return an empty frame without advancing its input. The decode loop then runs indefinitely, pins a worker at full CPU, and grows an ArrayBuffer without bound, resulting in denial of service. 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.