CVE-2021-29421 Explained : Impact and Mitigation

This article provides an in-depth understanding of CVE-2021-29421, including its impact, technical details, and mitigation strategies.

Understanding CVE-2021-29421

CVE-2021-29421 is related to a vulnerability in models/metadata.py within the pikepdf package versions 1.3.0 through 2.9.2 for Python. The vulnerability allows for XML External Entity (XXE) attacks during the parsing of XMP metadata entries.

What is CVE-2021-29421?

CVE-2021-29421 specifically affects the pikepdf package versions 1.3.0 through 2.9.2 for Python. It enables malicious actors to exploit XXE vulnerabilities by manipulating XMP metadata entries.

The Impact of CVE-2021-29421

The impact of CVE-2021-29421 allows threat actors to launch XXE attacks, potentially leading to information disclosure, server-side request forgery (SSRF), and other security risks for systems utilizing the vulnerable pikepdf package.

Technical Details of CVE-2021-29421

The technical details of CVE-2021-29421 include a description of the vulnerability, affected systems and versions, and the exploitation mechanism.

Vulnerability Description

The vulnerability resides in models/metadata.py in pikepdf versions 1.3.0 through 2.9.2, enabling XXE attacks by exploiting XMP metadata parsing.

Affected Systems and Versions

The vulnerability impacts versions 1.3.0 through 2.9.2 of the pikepdf package for Python.

Exploitation Mechanism

Malicious entities can exploit CVE-2021-29421 by crafting malicious XMP metadata entries to trigger XXE attacks during parsing.

Mitigation and Prevention

Understanding how to mitigate and prevent CVE-2021-29421 is crucial to safeguard vulnerable systems.

Immediate Steps to Take

Immediately update the pikepdf package to a non-vulnerable version and apply security patches to mitigate the risk of XXE attacks.

Long-Term Security Practices

Regularly monitor security advisories and update dependencies to prevent similar vulnerabilities in the future.

Patching and Updates

Stay informed about security updates and patches released by the pikepdf maintainers to address CVE-2021-29421 and other security vulnerabilities.