{"id":"CVE-2026-69202","aliases":["EUVD-2026-79234","GHSA-6m4x-pp6q-5jmm"],"status":"published","title":"Http4s Ember HTTP/2: unbounded inbound body buffering","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/2 flow-control window is replenished according to bytes received from the network rather than bytes consumed by the application, while each stream stores DATA in an unbounded channel. A hostile peer can therefore send a body faster than a slow or non-draining application consumes it, retaining payloads in heap on an ember-server or ember-client configured with withHttp2. The patch bounds the per-stream H2Connection body channel so application consumption applies backpressure. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.0063,"percentile":0.5047,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400","CWE-770"],"published":"2026-09-15T19:25:13Z","modified":"2026-10-28T02:30:44Z","fixes":[{"ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.12","fixed_in":["0.23.35"],"sources":["ghsa","osv"]},{"ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.13","fixed_in":["0.23.35","1.0.0-M47"],"sources":["ghsa","osv"]},{"ecosystem":"Maven","package":"org.http4s:http4s-ember-core_3","fixed_in":["0.23.35","1.0.0-M47"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.12","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.23.34"},{"fixed":"0.23.35"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.23.34"},{"fixed":"0.23.35"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.23.34"},{"fixed":"0.23.35"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0-M1"},{"last_affected":"1.0.0-M46"},{"fixed":"1.0.0-M47"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0-M1"},{"last_affected":"1.0.0-M46"},{"fixed":"1.0.0-M47"}]}]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.12","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.23.35"}]}],"versions":["0.10.0-M10","0.21.0","0.21.0-M2","0.21.0-M3","0.21.0-M4","0.21.0-M5","0.21.0-M6","0.21.0-RC1","0.21.0-RC2","0.21.0-RC3","0.21.0-RC4","0.21.0-RC5","0.21.1","0.21.11","0.21.12","0.21.13","0.21.14","0.21.15","0.21.16","0.21.17","0.21.18","0.21.19","0.21.2","0.21.20","0.21.21","0.21.22","0.21.23","0.21.24","0.21.25","0.21.26","0.21.27","0.21.28","0.21.29","0.21.3","0.21.30","0.21.31","0.21.32","0.21.33","0.21.34","0.21.4","0.21.5","0.21.6","0.21.7","0.21.8","0.21.9","0.22-129-24d065b","0.22-143-49b5a8d","0.22-53-01128f5","0.22-96-55d3184","0.22.0","0.22.0-M1","0.22.0-M2","0.22.0-M3","0.22.0-M4","0.22.0-M5","0.22.0-M6","0.22.0-M7","0.22.0-M8","0.22.0-RC1","0.22.1","0.22.10","0.22.11","0.22.12","0.22.13","0.22.14","0.22.15","0.22.2","0.22.3","0.22.4","0.22.5","0.22.6","0.22.7","0.22.8","0.22.9","0.23.0","0.23.0-M1","0.23.0-RC1","0.23.1","0.23.10","0.23.11","0.23.12","0.23.13","0.23.14","0.23.15","0.23.16","0.23.17","0.23.18","0.23.19","0.23.19-RC1","0.23.19-RC2","0.23.19-RC3","0.23.2","0.23.20","0.23.21","0.23.22","0.23.23","0.23.24","0.23.25","0.23.26","0.23.27","0.23.28","0.23.29","0.23.3","0.23.30","0.23.31","0.23.32","0.23.33","0.23.34","0.23.4","0.23.5","0.23.6","0.23.7","0.23.8","0.23.9"]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_2.13","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.23.35"}]}],"versions":["0.10.0-M10","0.21.0","0.21.0-M2","0.21.0-M3","0.21.0-M4","0.21.0-M5","0.21.0-M6","0.21.0-RC1","0.21.0-RC2","0.21.0-RC3","0.21.0-RC4","0.21.0-RC5","0.21.1","0.21.11","0.21.12","0.21.13","0.21.14","0.21.15","0.21.16","0.21.17","0.21.18","0.21.19","0.21.2","0.21.20","0.21.21","0.21.22","0.21.23","0.21.24","0.21.25","0.21.26","0.21.27","0.21.28","0.21.29","0.21.3","0.21.30","0.21.31","0.21.32","0.21.33","0.21.34","0.21.4","0.21.5","0.21.6","0.21.7","0.21.8","0.21.9","0.22-129-24d065b","0.22-143-49b5a8d","0.22-53-01128f5","0.22-96-55d3184","0.22.0","0.22.0-M1","0.22.0-M2","0.22.0-M3","0.22.0-M4","0.22.0-M5","0.22.0-M6","0.22.0-M7","0.22.0-M8","0.22.0-RC1","0.22.1","0.22.10","0.22.11","0.22.12","0.22.13","0.22.14","0.22.15","0.22.2","0.22.3","0.22.4","0.22.5","0.22.6","0.22.7","0.22.8","0.22.9","0.23.0","0.23.0-M1","0.23.0-RC1","0.23.1","0.23.10","0.23.11","0.23.12","0.23.13","0.23.14","0.23.15","0.23.16","0.23.17","0.23.18","0.23.19","0.23.19-RC1","0.23.19-RC2","0.23.19-RC3","0.23.2","0.23.20","0.23.21","0.23.22","0.23.23","0.23.24","0.23.25","0.23.26","0.23.27","0.23.28","0.23.29","0.23.3","0.23.30","0.23.31","0.23.32","0.23.33","0.23.34","0.23.4","0.23.5","0.23.6","0.23.7","0.23.8","0.23.9"]},{"source":"osv","ecosystem":"Maven","package":"org.http4s:http4s-ember-core_3","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.23.35"}]}],"versions":["0.22.0","0.22.0-M8","0.22.0-RC1","0.22.1","0.22.10","0.22.11","0.22.12","0.22.13","0.22.14","0.22.15","0.22.2","0.22.3","0.22.4","0.22.5","0.22.6","0.22.7","0.22.8","0.22.9","0.23.0","0.23.0-M1","0.23.0-RC1","0.23.1","0.23.10","0.23.11","0.23.12",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Ember HTTP/2: unbounded inbound body buffering","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/2 flow-control window is replenished according to bytes received from the network rather than bytes consumed by the application, while each stream stores DATA in an unbounded channel. A hostile peer can therefore send a body faster than a slow or non-draining application consumes it, retaining payloads in heap on an ember-server or ember-client configured with withHttp2. The patch bounds the per-stream H2Connection body channel so application consumption applies backpressure. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:25:13.258Z","modified":"2026-09-15T19:39:12.966Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T13:50:16.178634Z"}],"euvd":[{"id":"EUVD-2026-79234","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/2 flow-control window is replenished according to bytes received from the network rather than bytes consumed by the application, while each stream stores DATA in an unbounded channel. A hostile peer can therefore send a body faster than a slow or non-draining application consumes it, retaining payloads in heap on an ember-server or ember-client configured with withHttp2. The patch bounds the per-stream H2Connection body channel so application consumption applies backpressure. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:25:13Z","modified":"2026-09-15T19:39:12Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T17:28:16.983725Z"}],"ghsa":[{"id":"GHSA-6m4x-pp6q-5jmm","title":"Http4s Ember HTTP/2: unbounded inbound body buffering","description":"Ember's HTTP/2 stack replenishes the inbound flow-control window based on bytes\nreceived off the wire, not bytes consumed by the application.  Received DATA is buffered in an unbounded per-stream channel.  Flow control therefore\nprovides 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.\n\nThis is the read-path mirror of the [outbound queue issue](https://github.com/http4s/http4s/security/advisories/GHSA-8f3q-3jmv-7prw).\n\nThis affects an Ember receiving a request body and an Ember client receiving a response body from a hostile server.\n\n### Impact\n\nUnauthenticated remote denial of service (OOM) against any Ember server built\n`.withHttp2` for a non-draining or slow-draining route, and against an Ember client consuming from a hostile or compromised server.\n\n### Workarounds\n\n- Disable HTTP/2 to remove the vector entirely.\n- Apply an aggregate request-entity size limit (e.g. `EntityLimiter` middleware) on routes that consume the body.\n- Ensure handlers fully drain request bodies with aggressive idle timeouts.","status":"published","published":"2026-09-15T19:52:58Z","modified":"2026-09-15T19:52:59Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T14:41:17.136201Z"}],"nvd":[{"id":"CVE-2026-69202","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/2 flow-control window is replenished according to bytes received from the network rather than bytes consumed by the application, while each stream stores DATA in an unbounded channel. A hostile peer can therefore send a body faster than a slow or non-draining application consumes it, retaining payloads in heap on an ember-server or ember-client configured with withHttp2. The patch bounds the per-stream H2Connection body channel so application consumption applies backpressure. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T20:17:38.55Z","modified":"2026-09-16T20:38:04.943Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T14:12:47.974509Z"}],"osv":[{"id":"CVE-2026-69202","title":"Http4s Ember HTTP/2: unbounded inbound body buffering","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/2 flow-control window is replenished according to bytes received from the network rather than bytes consumed by the application, while each stream stores DATA in an unbounded channel. A hostile peer can therefore send a body faster than a slow or non-draining application consumes it, retaining payloads in heap on an ember-server or ember-client configured with withHttp2. The patch bounds the per-stream H2Connection body channel so application consumption applies backpressure. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:25:13.258Z","modified":"2026-10-28T02:30:44.359398984Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T15:45:15.164658Z"},{"id":"GHSA-6m4x-pp6q-5jmm","title":"Http4s Ember HTTP/2: unbounded inbound body buffering","description":"Ember's HTTP/2 stack replenishes the inbound flow-control window based on bytes\nreceived off the wire, not bytes consumed by the application.  Received DATA is buffered in an unbounded per-stream channel.  Flow control therefore\nprovides 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.\n\nThis is the read-path mirror of the [outbound queue issue](https://github.com/http4s/http4s/security/advisories/GHSA-8f3q-3jmv-7prw).\n\nThis affects an Ember receiving a request body and an Ember client receiving a response body from a hostile server.\n\n### Impact\n\nUnauthenticated remote denial of service (OOM) against any Ember server built\n`.withHttp2` for a non-draining or slow-draining route, and against an Ember client consuming from a hostile or compromised server.\n\n### Workarounds\n\n- Disable HTTP/2 to remove the vector entirely.\n- Apply an aggregate request-entity size limit (e.g. `EntityLimiter` middleware) on routes that consume the body.\n- Ensure handlers fully drain request bodies with aggressive idle timeouts.","status":"published","published":"2026-09-15T19:52:58Z","modified":"2026-09-15T20:00:39.604763254Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T15:46:39.965326Z"}]}}