CVE-2021-39242 : Vulnerability Insights and Analysis

An issue was discovered in HAProxy versions 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3, potentially allowing an attacker-controlled HTTP Host header.

Understanding CVE-2021-39242

This CVE involves a vulnerability in HAProxy versions that mishandles a mismatch between Host and authority in the HTTP header.

What is CVE-2021-39242?

The vulnerability in HAProxy versions before 2.2.16, 2.3.13, and 2.4.3 can be exploited by an attacker to control the HTTP Host header.

The Impact of CVE-2021-39242

This vulnerability could lead to a situation where an attacker controls the HTTP Host header.

Technical Details of CVE-2021-39242

HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3 are affected by this CVE.

Vulnerability Description

The issue arises due to the mishandling of a mismatch between the Host and authority in the HTTP header.

Affected Systems and Versions

HAProxy versions: 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3.

Exploitation Mechanism

An attacker can exploit this vulnerability by manipulating the HTTP Host header to gain control.

Mitigation and Prevention

Immediate Steps to Take:

Update HAProxy to the latest versions (2.2.16, 2.3.13, or 2.4.3) to prevent exploitation.

Long-Term Security Practices:

Regularly monitor for security advisories and update systems promptly.
Implement secure coding practices to mitigate similar vulnerabilities.
Conduct thorough security assessments and penetration testing.
Enforce the principle of least privilege to limit potential attack surfaces.

Patching and Updates:

Apply patches released by HAProxy promptly to address this vulnerability.