CVE-2021-41084 : Exploit Details and Defense Strategies

http4s is an open-source Scala interface for HTTP. The vulnerability in affected versions allows response-splitting or request-splitting attacks. Sanitizing user input in specific fields is essential to prevent exploitation.

Understanding CVE-2021-41084

This CVE identifies a vulnerability in http4s that enables response-splitting or request-splitting attacks, potentially leading to security threats.

What is CVE-2021-41084?

http4s, a Scala interface for HTTP, is prone to response-splitting or request-splitting attacks when untrusted user input affects certain fields, leaving systems vulnerable to exploit. Versions 0.21.30, 0.22.5, 0.23.4, and 1.0.0-M27 have addressed this vulnerability.

The Impact of CVE-2021-41084

The vulnerability poses a high-risk security threat, with a CVSS base score of 8.7, impacting confidentiality, integrity, and altering the scope, potentially leading to network-based attacks.

Technical Details of CVE-2021-41084

http4s versions <= 0.21.28, >= 0.22.0 and < 0.22.5, >= 0.23.0 and < 0.23.4, >= 1.0.0-M1 and < 1.0.0-M27 are affected by this vulnerability.

Vulnerability Description

The vulnerability allows for response-splitting or request-splitting attacks due to unsanitized user input in specific fields like Header names, values, URI paths, and more.

Affected Systems and Versions

Versions <= 0.21.28
Versions >= 0.22.0 and < 0.22.5
Versions >= 0.23.0 and < 0.23.4
Versions >= 1.0.0-M1 and < 1.0.0-M27

Exploitation Mechanism

Untrusted user input manipulation in critical HTTP fields

Mitigation and Prevention

Take immediate steps and adopt long-term security practices to mitigate risks and ensure system integrity.

Immediate Steps to Take

Update http4s to versions 0.21.30, 0.22.5, 0.23.4, or 1.0.0-M27
Sanitize user input in header fields to prevent attacks

Long-Term Security Practices

Regular security vulnerability assessments and audits
Implement input validation and sanitation procedures
Monitor and restrict user input manipulation

Patching and Updates

Apply security patches promptly
Stay updated with the latest releases and security advisories