Http4s Ember HTTP/2 does not enforce SETTINGS_MAX_CONCURRENT_STREAMS

An ember server with HTTP/2 enabled .withHttp2 does not enforce SETTINGSMAXCONCURRENTSTREAMS on streams opened by the peer. A single unauthenticated connection can open an unbounded number of concurrent streams, each of which allocates per-stream server state that is never released, exhausting th...

GHSA-6M4X-PP6Q-5JMM 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...

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...

CVE-2026-88975 Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE

Http4s is a Scala interface for HTTP services. Prior to 0.23.37 and 1.0.0-M48, Ember’s HTTP/2 read loop parses a frame’s 24-bit declared length but waits to buffer the entire payload before comparing it with SETTINGSMAXFRAMESIZE. An unauthenticated peer can declare a payload near 16 MiB on a...

CVE-2026-88975

Http4s (a Scala HTTP library) is vulnerable in Ember's HTTP/2 read loop prior to versions 0.23.37 and 1.0.0-M48 . The loop parses a frame's 24-bit declared length but buffers the entire payload before comparing it against SETTINGS_MAX_FRAME_SIZE . An unauthenticated peer can declare a payload nea...

EUVD-2026-79239

Http4s is a Scala interface for HTTP services. Prior to 0.23.37 and 1.0.0-M48, Ember’s HTTP/2 read loop parses a frame’s 24-bit declared length but waits to buffer the entire payload before comparing it with SETTINGSMAXFRAMESIZE. An unauthenticated peer can declare a payload near 16 MiB on a...

CVE-2026-69202 Http4s Ember HTTP/2: unbounded inbound body buffering

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...

CVE-2026-69202

Http4s is a Scala HTTP services library. In versions prior to 0.23.35 and 1.0.0-M47 , Ember's HTTP/2 flow-control window is replenished based on bytes received from the network rather than bytes consumed by the application, and each stream stores DATA in an unbounded channel . A remote peer can t...

EUVD-2026-79234

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...

CVE-2026-69202 Http4s Ember HTTP/2: unbounded inbound body buffering

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...

CVE-2026-69218 Http4s Ember HTTP/2: unbounded continuation frame accumulation

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 PUSHPROMISE frame without ENDHEADERS, H2Connection buffers the header block and subsequent CONTINUATION fragments without a size bound. A remote peer can keep an incomplete bloc...

CVE-2026-69218 Http4s Ember HTTP/2: unbounded continuation frame accumulation

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 PUSHPROMISE frame without ENDHEADERS, H2Connection buffers the header block and subsequent CONTINUATION fragments without a size bound. A remote peer can keep an incomplete bloc...

CVE-2026-69218

Http4s Ember HTTP/2 is vulnerable to unbounded continuation frame accumulation in its H2Connection component. When Ember receives an HTTP/2 HEADERS or PUSH_PROMISE frame without END_HEADERS, it buffers the header block and subsequent CONTINUATION fragments without a size bound . A remote peer can...

EUVD-2026-79195

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 PUSHPROMISE frame without ENDHEADERS, H2Connection buffers the header block and subsequent CONTINUATION fragments without a size bound. A remote peer can keep an incomplete bloc...

CVE-2026-69203 Http4s Ember HTTP/2: does not enforce SETTINGS_MAX_CONCURRENT_STREAMS

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, An Ember server with HTTP/2 enabled through withHttp2 does not enforce SETTINGSMAXCONCURRENTSTREAMS for peer-created streams. One unauthenticated connection can open an unbounded number of streams, each retaining...

CVE-2026-69203

Http4s is a Scala HTTP service library. Prior to versions 0.23.35 and 1.0.0-M47 , its Ember server with HTTP/2 enabled via withHttp2 does not enforce SETTINGS_MAX_CONCURRENT_STREAMS for peer-created streams. A single unauthenticated connection can open an unbounded number of streams, each retaini...

EUVD-2026-79194

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, An Ember server with HTTP/2 enabled through withHttp2 does not enforce SETTINGSMAXCONCURRENTSTREAMS for peer-created streams. One unauthenticated connection can open an unbounded number of streams, each retaining...

CVE-2026-69203 Http4s Ember HTTP/2: does not enforce SETTINGS_MAX_CONCURRENT_STREAMS

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, An Ember server with HTTP/2 enabled through withHttp2 does not enforce SETTINGSMAXCONCURRENTSTREAMS for peer-created streams. One unauthenticated connection can open an unbounded number of streams, each retaining...

CVE-2026-69203 Http4s Ember HTTP/2: does not enforce SETTINGS_MAX_CONCURRENT_STREAMS

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, An Ember server with HTTP/2 enabled through withHttp2 does not enforce SETTINGSMAXCONCURRENTSTREAMS for peer-created streams. One unauthenticated connection can open an unbounded number of streams, each retaining...

CVE-2026-69213

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...