CVE-2025-59822

23.09.2025, 19:15

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.

HTTP Request/Response Smuggling

Provider	Type	Base Score	Vector
NIST	NIST	UNKNOWN	---
GitHub_M	CNA	---	---
CISA-ADP	ADP	---	---

Awaiting analysis

This vulnerability is currently awaiting analysis.

Base Score

CVSS 3.x

EPSS Score

Percentile: Unknown

Common Weakness Enumeration

CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

References

https://github.com/http4s/http4s/commit/dd518f7c967e5165813b8d4a48a82b8fab852d41

https://github.com/http4s/http4s/security/advisories/GHSA-wcwh-7gfw-5wrr