Http4s Ember HTTP/2: unbounded inbound body buffering
Ember's HTTP/2 stack replenishes the inbound flow-control window based on bytes received off the wire, not bytes consumed by the application. Received DATA is buffered in an unbounded per-stream channel. Flow control therefore provides no backpressure: a peer can stream a large or unbounded body faster than the application drains it and the connection retains every payload in heap.
This is the read-path mirror of the outbound queue issue.
This affects an Ember receiving a request body and an Ember client receiving a response body from a hostile server.
Impact
Unauthenticated remote denial of service (OOM) against any Ember server built
.withHttp2 for a non-draining or slow-draining route, and against an Ember client consuming from a hostile or compromised server.
Workarounds
- Disable HTTP/2 to remove the vector entirely.
- Apply an aggregate request-entity size limit (e.g.
EntityLimitermiddleware) on routes that consume the body. - Ensure handlers fully drain request bodies with aggressive idle timeouts.
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Java / Kotlin (Maven) | org.http4s:http4s-ember-core_2.12 | < 0.23.35 | 0.23.35 |
| Java / Kotlin (Maven) | org.http4s:http4s-ember-core_2.13 | < 0.23.35, >= 1.0.0-M1, < 1.0.0-M47 | 0.23.35, 1.0.0-M47 |
| Java / Kotlin (Maven) | org.http4s:http4s-ember-core_3 | < 0.23.35, >= 1.0.0-M1, < 1.0.0-M47 | 0.23.35, 1.0.0-M47 |
Referencias
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Debilidad (CWE)
CWE-400, CWE-770- Plataforma
- Java / Kotlin (Maven)
- Paquete
org.http4s:http4s-ember-core_2.12, org.http4s:http4s-ember-core_2.13, org.http4s:http4s-ember-core_3- Publicada
- 15.09.2026
- Actualizado
- 11.10.2026 13:20
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-6m4x-pp6q-5jmm - CC BY 4.0
Historial de vulnerabilidades: org.http4s:http4s-ember-core_2.12
Todas las vulnerabilidades publicadas de este paquete (Java / Kotlin (Maven)), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 11
- Primera → última
- 09.2025 09.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Crítica 1
- Alta 7
- Media 3
Divulgaciones por año
- 2025: 1
- 2026: 10
-
Http4s Ember HTTP/2: unbounded inbound body buffering esta entrada
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