Typelevel CVEs with a proof of concept

CVE	Severity	Published▾	Status	Exploitation	Description
CVE-2025-59822	Medium	2025-09-23	No exploit published	Proof of concept only	Http4s is a Scala interface for HTTP services. In versions from 1.0.0-M1 to before 1.0.0-M45 and before 0.23.31, http4s is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section. This vulnerability could enable attackers to bypass front-end servers security controls, launch targeted attacks against active users, and poison web caches. A pre-requisite for exploitation involves the web application being deployed behind a reverse-proxy that forwards trailer headers. This issue has been patched in versions 1.0.0-M45 and 0.23.31.
CVE-2023-22465	High	2023-01-04	No exploit published	Proof of concept only	Http4s is a Scala interface for HTTP services. Starting with version 0.1.0 and prior to versions 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38, the `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs. In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38. As a workaround, use the weakly typed header interface.
CVE-2022-31183	Critical	2022-08-01	No exploit published	Proof of concept only	fs2 is a compositional, streaming I/O library for Scala. When establishing a server-mode `TLSSocket` using `fs2-io` on Node.js, the parameter `requestCert = true` is ignored, peer certificate verification is skipped, and the connection proceeds. The vulnerability is limited to: 1. `fs2-io` running on Node.js. The JVM TLS implementation is completely independent. 2. `TLSSocket`s in server-mode. Client-mode `TLSSocket`s are implemented via a different API. 3. mTLS as enabled via `requestCert = true` in `TLSParameters`. The default setting is `false` for server-mode `TLSSocket`s. It was introduced with the initial Node.js implementation of fs2-io in 3.1.0. A patch is released in v3.2.11. The requestCert = true parameter is respected and the peer certificate is verified. If verification fails, a SSLException is raised. If using an unpatched version on Node.js, do not use a server-mode TLSSocket with requestCert = true to establish a mTLS connection.
CVE-2022-21653	High	2022-01-05	No exploit published	Proof of concept only	Jawn is an open source JSON parser. Extenders of the `org.typelevel.jawn.SimpleFacade` and `org.typelevel.jawn.MutableFacade` who don't override `objectContext()` are vulnerable to a hash collision attack which may result in a denial of service. Most applications do not implement these traits directly, but inherit from a library. `jawn-parser-1.3.1` fixes this issue and users are advised to upgrade. For users unable to upgrade override `objectContext()` to use a collision-safe collection.

CVE

Severity

Published▾

Status

Exploitation

Description

CVE-2025-59822

Medium

2025-09-23

No exploit published

Proof of concept only

Http4s is a Scala interface for HTTP services. In versions from 1.0.0-M1 to before 1.0.0-M45 and before 0.23.31, http4s is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section. This vulnerability could enable attackers to bypass front-end servers security controls, launch targeted attacks against active users, and poison web caches. A pre-requisite for exploitation involves the web application being deployed behind a reverse-proxy that forwards trailer headers. This issue has been patched in versions 1.0.0-M45 and 0.23.31.

CVE-2023-22465

High

2023-01-04

No exploit published

Proof of concept only

Http4s is a Scala interface for HTTP services. Starting with version 0.1.0 and prior to versions 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38, the `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs. In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38. As a workaround, use the weakly typed header interface.

CVE-2022-31183

Critical

2022-08-01

No exploit published

Proof of concept only

fs2 is a compositional, streaming I/O library for Scala. When establishing a server-mode `TLSSocket` using `fs2-io` on Node.js, the parameter `requestCert = true` is ignored, peer certificate verification is skipped, and the connection proceeds. The vulnerability is limited to: 1. `fs2-io` running on Node.js. The JVM TLS implementation is completely independent. 2. `TLSSocket`s in server-mode. Client-mode `TLSSocket`s are implemented via a different API. 3. mTLS as enabled via `requestCert = true` in `TLSParameters`. The default setting is `false` for server-mode `TLSSocket`s. It was introduced with the initial Node.js implementation of fs2-io in 3.1.0. A patch is released in v3.2.11. The requestCert = true parameter is respected and the peer certificate is verified. If verification fails, a SSLException is raised. If using an unpatched version on Node.js, do not use a server-mode TLSSocket with requestCert = true to establish a mTLS connection.

CVE-2022-21653

High

2022-01-05

No exploit published

Proof of concept only

Jawn is an open source JSON parser. Extenders of the `org.typelevel.jawn.SimpleFacade` and `org.typelevel.jawn.MutableFacade` who don't override `objectContext()` are vulnerable to a hash collision attack which may result in a denial of service. Most applications do not implement these traits directly, but inherit from a library. `jawn-parser-1.3.1` fixes this issue and users are advised to upgrade. For users unable to upgrade override `objectContext()` to use a collision-safe collection.