CVE-2021-39241 Explained : Impact and Mitigation

This CVE record pertains to an issue in HAProxy versions prior to specific releases. The vulnerability allows an HTTP method name to be manipulated to access protected resources.

Understanding CVE-2021-39241

HAProxy versions 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3 are affected by this security flaw.

What is CVE-2021-39241?

The vulnerability in HAProxy enables the exploitation of an HTTP method name to access protected resources, potentially leading to unauthorized access.

The Impact of CVE-2021-39241

The vulnerability may allow attackers to request protected resources by manipulating the HTTP method name, potentially compromising sensitive data or functions of the server.

Technical Details of CVE-2021-39241

HAProxy versions are affected as follows:

2.0 before 2.0.24
2.2 before 2.2.16
2.3 before 2.3.13
2.4 before 2.4.3

Vulnerability Description

An attacker can use a crafted HTTP method name to gain unauthorized access to protected resources by manipulating it within the request.

Affected Systems and Versions

All versions of HAProxy before 2.0.24, 2.2.16, 2.3.13, and 2.4.3 are susceptible to this vulnerability.

Exploitation Mechanism

By inserting a space in the HTTP method name followed by the desired protected resource, attackers can deceive the server into treating the request as legitimate.

Mitigation and Prevention

In response to CVE-2021-39241, the following steps are recommended:

Immediate Steps to Take

Update HAProxy to the latest patched version.
Monitor for any suspicious activity that could indicate an exploitation attempt.

Long-Term Security Practices

Implement strict input validation mechanisms in any web applications behind the HAProxy instance.
Regularly review and update security configurations to adapt to evolving threats.

Patching and Updates

Ensure timely application of security updates and patches provided by the HAProxy project to mitigate the vulnerability effectively.