CVE-2021-39371 Explained : Impact and Mitigation

This CVE-2021-39371 article provides details about an XML external entity (XXE) injection vulnerability affecting PyWPS before version 4.4.5 and potentially OWSLib 0.24.1.

Understanding CVE-2021-39371

CVE-2021-39371 is an XML external entity (XXE) injection vulnerability that allows an attacker to view files on the application server filesystem by assigning a path to the entity.

What is CVE-2021-39371?

Type: XML external entity (XXE) injection vulnerability
Affected Software: PyWPS before 4.4.5, potentially OWSLib 0.24.1
Attack Vector: Remote

The Impact of CVE-2021-39371

This vulnerability allows attackers to access and view files on the application server's filesystem, potentially exposing sensitive information and compromising the security of the system.

Technical Details of CVE-2021-39371

CVE-2021-39371 affects certain versions of PyWPS and OWSLib, leading to the following technical aspects:

Vulnerability Description

An XML external entity (XXE) injection in PyWPS before 4.4.5 allows an attacker to view files on the application server filesystem by assigning a path to the entity. OWSLib 0.24.1 may also be affected.

Affected Systems and Versions

Affected Software: PyWPS before 4.4.5, OWSLib 0.24.1
Vendor: N/A
Product: N/A
Versions: N/A

Exploitation Mechanism

The vulnerability can be exploited remotely by injecting malicious XML external entities, tricking the application to reveal files on the server filesystem.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-39371, consider the following steps:

Immediate Steps to Take

Update PyWPS to version 4.4.5 or newer.
Apply relevant patches and security updates from the software vendor.
Monitor and restrict access to sensitive directories and files.

Long-Term Security Practices

Conduct regular security assessments and penetration testing.
Implement strict input validation mechanisms to prevent XXE attacks.
Stay informed about security advisories and updates related to PyWPS and OWSLib.
Consider security training for developers to increase awareness of secure coding practices.

Patching and Updates

Regularly check for security updates and patches from PyWPS and OWSLib to address vulnerabilities and ensure the latest security measures are in place.