CVE-2026-69218

Http4s Ember HTTP/2: unbounded continuation frame accumulation

Published: Sep 15, 2026Updated: Sep 17, 2026 Sources: CVE List NVDCWE-770

7.5HIGH

Description

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, When Ember receives an HTTP/2 HEADERS or PUSH_PROMISE frame without END_HEADERS, H2Connection buffers the header block and subsequent CONTINUATION fragments without a size bound. A remote peer can keep an incomplete block open and exhaust heap memory before request decoding, affecting an ember-server or ember-client configured with withHttp2. The remediation tracks accumulated size against SETTINGS_MAX_HEADER_LIST_SIZE derived from EmberServerBuilder.maxHeaderSize or EmberClientBuilder.maxResponseHeaderSize, sends GOAWAY when the limit is exceeded, and applies receiveHeadersTimeout to incomplete blocks. 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-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

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MITRE ATT&CK

1 technique

Impact

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References

https://github.com/http4s/http4s/commit/6e8eccd64a6a74ab4811897881e95e0e1b3a818e

github.com

https://github.com/http4s/http4s/commit/f9dcca4f5a17992ac0972fafd7920f9bc12cdc51

github.com

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

github.com

and 2 more references View all →

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