CVE-2026-69202

Http4s Ember HTTP/2: unbounded inbound body buffering

Published: Sep 15, 2026Updated: Sep 16, 2026 Sources: CVE List NVDCWE-400

7.5HIGH

Description

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/2 flow-control window is replenished according to bytes received from the network rather than bytes consumed by the application, while each stream stores DATA in an unbounded channel. A hostile peer can therefore send a body faster than a slow or non-draining application consumes it, retaining payloads in heap on an ember-server or ember-client configured with withHttp2. The patch bounds the per-stream H2Connection body channel so application consumption applies backpressure. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:NConfidentiality

None

I:NIntegrity

None

A:HAvailability

High

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Weaknesses

CWE-400 CWE-770

Affected Products

http4s

oss-projectaka blaze

http4sLibrary

OSS Libraries / web-framework

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique

Impact

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References

https://github.com/http4s/http4s/security/advisories/GHSA-6m4x-pp6q-5jmm

github.com

https://github.com/http4s/http4s/commit/22d2335975d02dc9fb9fb75cfe002279521d86ac

github.com

https://github.com/http4s/http4s/releases/tag/v0.23.35

github.com

and 1 more references View all →

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