CVE-2026-69218
Http4s Ember HTTP/2: unbounded continuation frame accumulation
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| maven | org.http4s:http4s-ember-core_2.12 | <= 0.23.34 | 0.23.35 |
| maven | org.http4s:http4s-ember-core_2.13 | <= 0.23.34 | 0.23.35 |
| maven | org.http4s:http4s-ember-core_3 | <= 0.23.34 | 0.23.35 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-cp4q-fqw9-4hf6
- https://github.com/http4s/http4s/security/advisories/GHSA-cp4q-fqw9-4hf6
- https://github.com/http4s/http4s/commit/6e8eccd64a6a74ab4811897881e95e0e1b3a818e
- https://github.com/http4s/http4s/releases/tag/v0.23.35
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M47
- https://github.com/http4s/http4s/commit/f9dcca4f5a17992ac0972fafd7920f9bc12cdc51