CVE-2019-9023 : Security Advisory and Response

A vulnerability has been discovered in several versions of PHP (before 5.6.40, 7.x before 7.1.26, 7.2.x before 7.2.14, and 7.3.x before 7.3.1) involving heap-based buffer over-read instances in mbstring regular expression functions.

Understanding CVE-2019-9023

This CVE involves a vulnerability in PHP versions prior to 5.6.40, 7.x before 7.1.26, 7.2.x before 7.2.14, and 7.3.x before 7.3.1 related to multibyte regular expression functions.

What is CVE-2019-9023?

The vulnerability in PHP versions allows for heap-based buffer over-read instances in mbstring regular expression functions when invalid multibyte data is supplied, leading to potential security risks.

The Impact of CVE-2019-9023

The vulnerability can be exploited to trigger heap-based buffer over-read instances, potentially leading to unauthorized access, data leaks, or denial of service.

Technical Details of CVE-2019-9023

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The vulnerability involves heap-based buffer over-read instances in mbstring regular expression functions due to invalid multibyte data, affecting specific PHP files.

Affected Systems and Versions

PHP versions before 5.6.40
PHP 7.x before 7.1.26
PHP 7.2.x before 7.2.14
PHP 7.3.x before 7.3.1

Exploitation Mechanism

The vulnerability is triggered when multibyte regular expression patterns contain invalid multibyte sequences, leading to heap-based buffer over-read instances.

Mitigation and Prevention

Protect your systems from CVE-2019-9023 with the following measures:

Immediate Steps to Take

Update PHP to versions 5.6.40, 7.1.26, 7.2.14, or 7.3.1, which contain patches for the vulnerability.
Monitor for any unusual activities on the system that could indicate exploitation.

Long-Term Security Practices

Regularly update PHP and other software to the latest versions to patch known vulnerabilities.
Implement secure coding practices to prevent buffer over-read vulnerabilities.

Patching and Updates

Apply the latest patches provided by PHP to address the heap-based buffer over-read vulnerability.