CVE-2026-69210 Details
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.
A denial-of-service vulnerability has been identified in Http4s, a Scala library for HTTP services, in versions prior to 0.23.35 and 1.0.0-M47. The issue arises in the WebSocket FrameTranscoder, which improperly validates extended payload lengths. While it correctly rejects lengths exceeding Integer.MAX_VALUE, it allows negative 64-bit lengths. This flaw can be exploited by a remote client that completes a WebSocket handshake through an Ember server, sending a frame with a negative length. The decoder then returns an empty frame without processing the input, causing an infinite loop that consumes full CPU and unbounded memory, ultimately leading to a denial-of-service condition.
Users should upgrade to Http4s version 0.23.35 or 1.0.0-M47.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 15, 2026CISA-ADP
Assessed Sep 17, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/http4s/http4s/commit/c7d3ef90dc2ed1cd464968ab1b34f2f1762ddae2 | [email protected] | Source CodeVendor |
| https://github.com/http4s/http4s/releases/tag/v0.23.35 | [email protected] | Release NotesVendor |
| https://github.com/http4s/http4s/releases/tag/v1.0.0-M47 | [email protected] | Release NotesVendor |
| https://github.com/http4s/http4s/security/advisories/GHSA-3j86-pj9g-jchr | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-1284 | Improper Validation of Specified Quantity in Input | [email protected] |
| CWE-835 | Loop with Unreachable Exit Condition ('Infinite Loop') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| http4s | <= 0.23.34 (semver) >= 1.0.0-M1, <= 1.0.0-M46 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 17, 2026 | CVE Modified | CISA-ADP |
| Sep 15, 2026 | New CVE Received | [email protected] |