Denial of Service (DoS)

Overview Affected versions of this package are vulnerable to Denial of Service DoS through the WebSocket decoder process. An attacker can exhaust server memory by sending oversized frames or fragmented messages without size limits. Details Denial of Service DoS describes a family of attacks, all...

Denial of Service (DoS)

Overview Affected versions of this package are vulnerable to Denial of Service DoS through the WebSocket decoder process. An attacker can exhaust server memory by sending oversized frames or fragmented messages without size limits. Details Denial of Service DoS describes a family of attacks, all...

CVE-2026-69210 Http4s: WebSocket decoder accepts negative length, causing infinite decode loop

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, WebSocket FrameTranscoder.bodyLength rejects extended payload lengths above Integer.MAXVALUE but permits negative 64-bit lengths. A remote client that completes a WebSocket handshake through an Ember server can send su...

CVE-2026-69210

Http4s , a Scala HTTP service library, is vulnerable to a denial of service via its WebSocket decoder. In versions prior to 0.23.35 and 1.0.0-M47 , FrameTranscoder.bodyLength rejects extended payload lengths above Integer.MAX_VALUE but incorrectly permits negative 64-bit lengths . A remote client...

CVE-2026-69209

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, The shared WebSocket decoder permits unbounded message buffering because defragmentation accumulates fragments without a limit and FrameTranscoder accepts declared lengths up to Int.MaxValue. A remote client that...

EUVD-2026-79025

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember HTTP/1.1 does not reject messages containing both Transfer-Encoding and Content-Length, so an intermediary and Ember can select different body framing rules. When ember-server is behind a keep-alive intermediary...

HTTP Request Smuggling

Overview Affected versions of this package are vulnerable to HTTP Request Smuggling due to improper parsing of the HTTP trailer section in the parse function. An attacker can bypass security controls, launch targeted attacks against users, or poison web caches by crafting specially formed HTTP...

HTTP Request Smuggling

Overview Affected versions of this package are vulnerable to HTTP Request Smuggling due to improper parsing of the HTTP trailer section in the parse function. An attacker can bypass security controls, launch targeted attacks against users, or poison web caches by crafting specially formed HTTP...

HTTP Request Smuggling

Overview Affected versions of this package are vulnerable to HTTP Request Smuggling due to improper parsing of the HTTP trailer section in the parse function. An attacker can bypass security controls, launch targeted attacks against users, or poison web caches by crafting specially formed HTTP...

HTTP Request Smuggling

Overview Affected versions of this package are vulnerable to HTTP Request Smuggling due to improper parsing of the HTTP trailer section in the parse function. An attacker can bypass security controls, launch targeted attacks against users, or poison web caches by crafting specially formed HTTP...

HTTP Request Smuggling

Overview Affected versions of this package are vulnerable to HTTP Request Smuggling due to improper parsing of the HTTP trailer section in the parse function. An attacker can bypass security controls, launch targeted attacks against users, or poison web caches by crafting specially formed HTTP...

FS2 half-shutdown of socket during TLS handshake may result in spin loop on opposite side

Impact When establishing a TLS session using fs2-io on the JVM using the fs2.io.net.tls package, if one side of the connection shuts down write while the peer side is awaiting more data to progress the TLS handshake, the peer side will spin loop on the socket read, fully utilizing a CPU. This CPU...

PT-2025-36633

Impact When establishing a TLS session using fs2-io on the JVM using the fs2.io.net.tls package, if one side of the connection shuts down write while the peer side is awaiting more data to progress the TLS handshake, the peer side will spin loop on the socket read, fully utilizing a CPU. This CPU...

Unbounded connection acceptance in http4s-blaze-server

Impact blaze-core, a library underlying http4s-blaze-server, accepts connections unboundedly on its selector pool. This has the net effect of amplifying degradation in services that are unable to handle their current request load, since incoming connections are still accepted and added to an...

GHSA-XHV5-W9C5-2R2W Unbounded connection acceptance in http4s-blaze-server

Impact blaze-core, a library underlying http4s-blaze-server, accepts connections unboundedly on its selector pool. This has the net effect of amplifying degradation in services that are unable to handle their current request load, since incoming connections are still accepted and added to an...

Unbounded connection acceptance leads to file handle exhaustion

Impact All servers running blaze-core = 0.14.14, including blaze-http and http4s-blaze-server users, are affected. Blaze, accepts connections unconditionally on a dedicated thread pool. This has the net effect of amplifying degradation in services that are unable to handle their current request...

PT-2021-14396 · Unknown +2 · Blaze-Core +5

Name of the Vulnerable Software and Affected Versions: http4s versions prior to 0.21.17 http4s versions prior to 0.22.0-M2 http4s versions prior to 1.0.0-M14 Description: The issue is related to the blaze-core library, which accepts connections unboundedly on its selector pool. This can lead to a...