Which versions of Http4S are affected by CVE-2025-59822?

Organizations using versions from 1.0.0-M1 to should be aware of moderate risk from CVE-2025-59822 rated CVSS 6.3. Exploitation could compromise the security of affected deployments.. A patch is available.

Is there a public PoC exploit available for CVE-2025-59822?

Yes, a public proof-of-concept exploit is available for CVE-2025-59822. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2025-59822?

Within 30 days: Identify affected systems running versions from 1.0.0-M1 to and apply vendor patches as part of regular patch cycle. Vendor patch is available.

Http4S CVE-2025-59822

Q: What is the CVSS score of CVE-2025-59822?

CVE-2025-59822 has a CVSS 4.0 base score of 6.3 (Medium). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.1%.

MEDIUM

HTTP Request/Response Smuggling (CWE-444)

2025-09-23 security-advisories@github.com

Authentication Bypass Request Smuggling Http4S

6.3

CVSS 4.0 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

6.3 MEDIUM

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 19:13 vuln.today

Patch released

Mar 28, 2026 - 19:13 nvd

Patch available

PoC Detected

Oct 08, 2025 - 17:35 vuln.today

Public exploit code

CVE Published

Sep 23, 2025 - 19:15 nvd

MEDIUM 6.3

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

3 maven packages depend on org.http4s:http4s-ember-core_2.12 (2 direct, 1 indirect)

Ecosystem-wide dependent count for version 0.23.31.

DescriptionGitHub Advisory

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.

AnalysisAI

Http4s is a Scala interface for HTTP services. Rated medium severity (CVSS 6.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

Technical ContextAI

This vulnerability is classified as HTTP Request/Response Smuggling (CWE-444), which allows attackers to manipulate HTTP request interpretation between frontend and backend servers. 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. Affected products include: Typelevel Http4S. Version information: before 1.0.0.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Enforce strict HTTP parsing, normalize requests at proxy layer, use HTTP/2 end-to-end, reject ambiguous headers.