CVE-2022-39261 Explained : Impact and Mitigation

Twig may load a template outside a configured directory when using the filesystem loader.

Understanding CVE-2022-39261

Twig, a template language for PHP, is affected by a vulnerability that allows loading templates outside the configured directory when using the filesystem loader.

What is CVE-2022-39261?

Versions 1.x prior to 1.44.7, 2.x prior to 2.15.3, and 3.x prior to 3.4.3 of Twig encounter an issue where the filesystem loader loads templates with user input names. This can lead to reading arbitrary files outside the templates' directory, bypassing validation. The fixed versions include 1.44.7, 2.15.3, and 3.4.3.

The Impact of CVE-2022-39261

The vulnerability can result in the unauthorized access of files outside the intended directory structure, potentially leading to sensitive data exposure and security compromises.

Technical Details of CVE-2022-39261

Vulnerability Description

The issue arises from the filesystem loader in Twig, which fails to properly validate template names, allowing for path traversal and loading arbitrary files.

Affected Systems and Versions

Versions 1.x: => 1.0.0, < 1.44.7 (Affected)
Versions 2.x: >= 2.0.0, < 2.15.3 (Affected)
Versions 3.x: >= 3.0.0, < 3.4.3 (Affected)

Exploitation Mechanism

Malicious actors can exploit this vulnerability by manipulating template names with user input to include

@somewhere/../some.file

, enabling the access of unauthorized files.

Mitigation and Prevention

Immediate Steps to Take

To mitigate the risk associated with CVE-2022-39261, it is recommended to update Twig to versions 1.44.7, 2.15.3, or 3.4.3, which contain fixes for the validation issue.

Long-Term Security Practices

Implement input validation mechanisms and sanitize user input to prevent path traversal attacks. Regularly update software components to address known vulnerabilities.

Patching and Updates

Stay informed about security advisories and patch releases from TwigPHP to stay protected against potential security risks.