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.

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Tue, 15 Sep 2026 22:30:00 +0000

Type Values Removed Values Added
First Time appeared Http4s
Http4s http4s
Vendors & Products Http4s
Http4s http4s

Tue, 15 Sep 2026 19:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Http4s: WebSocket decoder accepts negative length, causing infinite decode loop
Weaknesses CWE-1284
CWE-835
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-15T19:19:04.868Z

Reserved: 2026-08-03T16:57:50.124Z

Link: CVE-2026-69210

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-15T20:17:40.320

Modified: 2026-09-15T20:17:40.320

Link: CVE-2026-69210

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-15T22:15:16Z

Weaknesses