high7.5
CVE-2026-69213
Http4s Ember HTTP/2 has an unbounded outbound frame queue
Impact
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember HTTP/2 serializes outbound frames through one unbounded queue consumed by writeLoop. When the peer stops reading, an unauthenticated HTTP/2 client can continue sending PING, SETTINGS, or DATA frames that cause Ember to enqueue acknowledgments or WINDOW_UPDATE frames faster than the writer drains them, exhausting heap memory on a server built with withHttp2. The shared behavior also affects an ember-client connected to a hostile HTTP/2 server, and the patch replaces the unbounded path with bounded, backpressured outbound queues. 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-8f3q-3jmv-7prw
- https://github.com/http4s/http4s/security/advisories/GHSA-8f3q-3jmv-7prw
- https://github.com/http4s/http4s/commit/13fe24d6440bde2f1eb70121486cf59c278e6bae
- https://github.com/http4s/http4s/releases/tag/v0.23.35
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M47