CVE-2019-9638 : Security Advisory and Response

A problem was detected in the EXIF module of PHP versions before 7.1.27, 7.2.x before 7.2.16, and 7.3.x before 7.3.3. This issue arises from an uninitialized reading occurring in the exif_process_IFD_in_MAKERNOTE function due to mishandling the relationship between the maker_note->offset and value_len.

Understanding CVE-2019-9638

What is CVE-2019-9638?

An issue was discovered in the EXIF component in PHP before 7.1.27, 7.2.x before 7.2.16, and 7.3.x before 7.3.3. There is an uninitialized read in exif_process_IFD_in_MAKERNOTE because of mishandling the maker_note->offset relationship to value_len.

The Impact of CVE-2019-9638

This vulnerability could allow an attacker to execute arbitrary code or cause a denial of service by exploiting the uninitialized read in the EXIF module of PHP.

Technical Details of CVE-2019-9638

Vulnerability Description

The vulnerability in the EXIF module of PHP versions before 7.1.27, 7.2.x before 7.2.16, and 7.3.x before 7.3.3 is due to mishandling the relationship between maker_note->offset and value_len, leading to uninitialized reads.

Affected Systems and Versions

PHP versions before 7.1.27
PHP 7.2.x before 7.2.16
PHP 7.3.x before 7.3.3

Exploitation Mechanism

The vulnerability can be exploited by an attacker to execute arbitrary code or trigger a denial of service by manipulating the uninitialized read in the EXIF module.

Mitigation and Prevention

Immediate Steps to Take

Update PHP to version 7.1.27, 7.2.16, or 7.3.3 or later to address the vulnerability.
Monitor official security advisories for patches and updates.

Long-Term Security Practices

Regularly update PHP and other software components to the latest versions.
Implement secure coding practices to prevent similar vulnerabilities.

Patching and Updates

Apply patches provided by PHP to fix the uninitialized read vulnerability in the EXIF module.