CVE-2019-25043 : Security Advisory and Response

ModSecurity 3.x versions prior to 3.0.4 mishandle key-value pair parsing, leading to a worker process crash when encountering specific headers.

Understanding CVE-2019-25043

This CVE involves a vulnerability in ModSecurity 3.x versions that can result in a worker process crash under certain conditions.

What is CVE-2019-25043?

The key-value pair parsing in ModSecurity 3.x versions before 3.0.4 is mishandled, causing a worker process crash when processing specific headers.

The Impact of CVE-2019-25043

The vulnerability can lead to a denial of service (DoS) condition due to the worker process crash, potentially affecting the availability of the system.

Technical Details of CVE-2019-25043

This section provides more technical insights into the CVE.

Vulnerability Description

ModSecurity 3.x versions prior to 3.0.4 mishandle key-value pair parsing, resulting in a worker process crash when encountering certain headers, such as "Cookie: =abc".

Affected Systems and Versions

Product: Not applicable
Vendor: Not applicable
Versions affected: All versions prior to 3.0.4

Exploitation Mechanism

The vulnerability is exploited by sending a specific malformed header, triggering the mishandling of key-value pairs and causing the worker process to crash.

Mitigation and Prevention

To address CVE-2019-25043, follow these mitigation strategies:

Immediate Steps to Take

Update ModSecurity to version 3.0.4 or later to mitigate the vulnerability.
Monitor for any abnormal worker process behavior that could indicate a potential exploit.

Long-Term Security Practices

Regularly update and patch ModSecurity to ensure the latest security fixes are in place.
Implement network-level protections to detect and block malicious traffic targeting this vulnerability.

Patching and Updates

Apply patches and updates provided by ModSecurity promptly to address known vulnerabilities and enhance system security.