CVE-2021-29425 : What You Need to Know

Apache Commons IO before 2.7 has a vulnerability in the method FileNameUtils.normalize, allowing path traversal with improper input strings like "//../foo". This CVE affects versions 2.2 to 2.6.

Understanding CVE-2021-29425

This section will cover the details of the CVE-2021-29425 vulnerability in Apache Commons IO.

What is CVE-2021-29425?

Apache Commons IO before 2.7 is vulnerable to a limited path traversal issue when using the FileNameUtils.normalize method with specific improper input strings.

The Impact of CVE-2021-29425

The vulnerability could potentially provide unauthorized access to files in the parent directory, allowing for a restricted path traversal attack.

Technical Details of CVE-2021-29425

In this section, we will delve into the technical aspects of the CVE-2021-29425 vulnerability.

Vulnerability Description

When invoking the FileNameUtils.normalize method with improper input strings, the resulting path may grant access to files in the parent directory (limited path traversal).

Affected Systems and Versions

Products like Apache Commons IO versions 2.2 to 2.6 are affected by CVE-2021-29425.

Exploitation Mechanism

The vulnerability arises from the FileNameUtils.normalize method not properly handling certain input strings, leading to path traversal issues.

Mitigation and Prevention

This section provides guidelines on how to mitigate and prevent exploitation of the CVE-2021-29425 vulnerability.

Immediate Steps to Take

Avoid passing unsafe input to FileNameUtils.normalize. Consider upgrading to Apache Commons IO 2.7 or later, where the method returns null for invalid input.

Long-Term Security Practices

Implement secure coding practices, input validation, and regular security updates to prevent similar vulnerabilities.

Patching and Updates

Ensure that Apache Commons IO is updated to version 2.7 or above to address CVE-2021-29425.