CVE-2020-5249 : Exploit Details and Defense Strategies

In Puma (RubyGem) before 4.3.3 and 3.12.4, a vulnerability allows attackers to inject malicious content via an early-hints header, known as HTTP Response Splitting.

Understanding CVE-2020-5249

This CVE pertains to a security issue in Puma that enables HTTP Response Splitting attacks.

What is CVE-2020-5249?

CVE-2020-5249 is a vulnerability in Puma that permits attackers to manipulate headers to inject malicious content, potentially leading to further attacks like cross-site scripting.

The Impact of CVE-2020-5249

CVSS Base Score: 6.5 (Medium Severity)
Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Changed
Confidentiality, Integrity, Availability Impact: Low
This vulnerability can be exploited by attackers to compromise the integrity of web applications and potentially execute cross-site scripting attacks.

Technical Details of CVE-2020-5249

This section provides detailed technical insights into the CVE.

Vulnerability Description

The vulnerability allows attackers to terminate headers prematurely, enabling the injection of malicious content.

Affected Systems and Versions

Affected Versions: Puma < 3.12.4, Puma >= 4.0.0, < 4.3.3

Exploitation Mechanism

Attackers can exploit this vulnerability by inserting a carriage return character to manipulate headers and inject malicious content.

Mitigation and Prevention

Protecting systems from CVE-2020-5249 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update Puma to version 4.3.3 or 3.12.4, where the vulnerability has been fixed.
Avoid accepting untrusted input in early-hints headers.

Long-Term Security Practices

Implement input validation mechanisms to sanitize user inputs.
Regularly monitor and update web application security configurations.

Patching and Updates

Apply patches provided by Puma to address the vulnerability and enhance security measures.