Http4s Ember HTTP/2: unbounded outbound frame queue

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-69213
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-15 19:17:38 UTC
Updated2026-09-17 17:16:46 UTC
DescriptionHttp4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember HTTP/2 serializes outbound frames through one unbounded queue consumed by writeLoop. When the peer stops reading, an unauthenticated HTTP/2 client can continue sending PING, SETTINGS, or DATA frames that cause Ember to enqueue acknowledgments or WINDOW_UPDATE frames faster than the writer drains them, exhausting heap memory on a server built with withHttp2. The shared behavior also affects an ember-client connected to a hostile HTTP/2 server, and the patch replaces the unbounded path with bounded, backpressured outbound queues. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.003610000 probability, percentile 0.296970000 (date 2026-09-16)

Problem Types: CWE-400 | CWE-770 | CWE-400 CWE-400: Uncontrolled Resource Consumption | CWE-770 CWE-770: Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Http4s Http4s affected < 0.23.35 Not specified
CNA Http4s Http4s affected >= 1.0.0-M1, < 1.0.0-M47 Not specified

References

ReferenceSourceLinkTags
github.com/http4s/http4s/releases/tag/v1.0.0-M47 [email protected] github.com
github.com/http4s/http4s/releases/tag/v0.23.35 [email protected] github.com
github.com/http4s/http4s/commit/13fe24d6440bde2f1eb70121486cf59c278e6bae [email protected] github.com
github.com/http4s/http4s/security/advisories/GHSA-8f3q-3jmv-7prw [email protected] github.com
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