Http4s Ember HTTP/2: does not enforce SETTINGS_MAX_CONCURRENT_STREAMS

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-69203
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-15 20:17:39 UTC
Updated2026-09-16 20:38:04 UTC
DescriptionHttp4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, An Ember server with HTTP/2 enabled through withHttp2 does not enforce SETTINGS_MAX_CONCURRENT_STREAMS for peer-created streams. One unauthenticated connection can open an unbounded number of streams, each retaining per-stream state until heap exhaustion. The same unchecked allocation is reachable in an ember-client through server-initiated PUSH_PROMISE frames because enablePush is not enforced. 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: 0.004600000 probability, percentile 0.389310000 (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/security/advisories/GHSA-9vwc-pc8p-253q [email protected] github.com
github.com/http4s/http4s/commit/4983de1f93f2caaa3b9de310cf6a9db32c50d66e [email protected] github.com
github.com/http4s/http4s/releases/tag/v0.23.35 [email protected] github.com
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