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OpenAdvisories
High · 7.5 CVE-2026-69218 EUVD-2026-79195GHSA-cp4q-fqw9-4hf6

Http4s Ember HTTP/2: unbounded continuation frame accumulation

Published Sep 15, 2026 · Updated Sep 17, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
http4s http4s < 0.23.35, >= 1.0.0-M1, < 1.0.0-M47 —

Affected packages

EcosystemPackageAffectedFixedRecord
Maven org.http4s:http4s-ember-core_2.12 < 0.23.35 0.23.35 GHSA-cp4q-fqw9-4hf6
Maven org.http4s:http4s-ember-core_2.13 < 0.23.35 0.23.35 GHSA-cp4q-fqw9-4hf6
Maven org.http4s:http4s-ember-core_2.13 >= 1.0.0-M1, < 1.0.0-M47 1.0.0-M47 GHSA-cp4q-fqw9-4hf6
Maven org.http4s:http4s-ember-core_3 < 0.23.35 0.23.35 GHSA-cp4q-fqw9-4hf6
Maven org.http4s:http4s-ember-core_3 >= 1.0.0-M1, < 1.0.0-M47 1.0.0-M47 GHSA-cp4q-fqw9-4hf6

References