CVE-2019-11038 : Security Advisory and Response

In versions of the PHP GD extension (7.1.x below 7.1.30, 7.2.x below 7.2.19, and 7.3.x below 7.3.6) that utilize the GD Graphics Library (LibGD) 2.2.5, there is a risk associated with the gdImageCreateFromXbm() function. When this function is used with certain data inputs, it can result in the utilization of an uninitialized variable value. Consequently, this may expose the contents of the stack that have been left behind by previous code execution.

Understanding CVE-2019-11038

This CVE involves an uninitialized read in gdImageCreateFromXbm function in PHP GD extension.

What is CVE-2019-11038?

CVE-2019-11038 is a vulnerability in PHP versions 7.1.x, 7.2.x, and 7.3.x that can lead to disclosure of stack contents due to the use of uninitialized variables.

The Impact of CVE-2019-11038

The vulnerability has a CVSS base score of 3.1, indicating a low severity issue with high attack complexity and network-based attack vector.

Technical Details of CVE-2019-11038

This section provides detailed technical information about the vulnerability.

Vulnerability Description

When using the gdImageCreateFromXbm() function in the GD Graphics Library (LibGD) 2.2.5, uninitialized variables can be accessed, potentially leading to disclosure of stack contents.

Affected Systems and Versions

Affected PHP versions: 7.1.x < 7.1.30, 7.2.x < 7.2.19, 7.3.x < 7.3.6
PHP GD extension utilizing LibGD 2.2.5

Exploitation Mechanism

The vulnerability requires enabling the gd extension and using gdImageCreateFromXbm() on externally controlled data to be exploited.

Mitigation and Prevention

Protecting systems from CVE-2019-11038 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply patches provided by PHP Group for the affected versions.
Monitor vendor advisories and update PHP to versions that address the vulnerability.

Long-Term Security Practices

Regularly update PHP and its extensions to the latest secure versions.
Implement secure coding practices to avoid uninitialized variable usage.

Patching and Updates

Refer to vendor advisories and security updates for PHP to patch the vulnerability.