CVE-2019-9637 : Vulnerability Insights and Analysis

A vulnerability was found in PHP versions prior to 7.1.27, 7.2.x prior to 7.2.16, and 7.3.x prior to 7.3.3. The way in which the rename() function operates when renaming files between filesystems creates the possibility for a temporary exposure of the renamed file with incorrect permissions, potentially allowing unauthorized users to access the data.

Understanding CVE-2019-9637

This CVE entry describes a security vulnerability in PHP versions prior to 7.1.27, 7.2.x prior to 7.2.16, and 7.3.x prior to 7.3.3.

What is CVE-2019-9637?

This vulnerability arises due to the way the rename() function handles file renaming across different filesystems, leading to a temporary exposure of the renamed file with incorrect permissions.

The Impact of CVE-2019-9637

The vulnerability could potentially enable unauthorized users to access sensitive data during the file renaming process.

Technical Details of CVE-2019-9637

This section provides more in-depth technical details of the CVE.

Vulnerability Description

The issue in PHP versions before 7.1.27, 7.2.x before 7.2.16, and 7.3.x before 7.3.3 allows unauthorized access to data due to incorrect permissions during the rename() function execution.

Affected Systems and Versions

PHP versions prior to 7.1.27
PHP 7.2.x versions prior to 7.2.16
PHP 7.3.x versions prior to 7.3.3

Exploitation Mechanism

Unauthorized users can exploit this vulnerability by accessing data during the brief exposure period when files are being renamed with incorrect permissions.

Mitigation and Prevention

Protect your systems from CVE-2019-9637 with the following steps:

Immediate Steps to Take

Update PHP to versions 7.1.27, 7.2.16, or 7.3.3 or later to patch the vulnerability.
Monitor file operations for any suspicious activities.

Long-Term Security Practices

Implement the principle of least privilege to restrict unauthorized access.
Regularly review and update file permissions to ensure data security.

Patching and Updates

Apply the latest patches and updates provided by PHP to address this vulnerability.