CVE-2021-29447 : Vulnerability Insights and Analysis

WordPress Authenticated XXE attack when installation is running PHP 8

Understanding CVE-2021-29447

This CVE refers to an XML External Entity (XXE) vulnerability in WordPress versions greater than or equal to 5.6.0 and less than 5.7.1, specifically when PHP 8 is in use. This vulnerability allows a user with file upload permissions to execute XXE attacks, potentially leading to unauthorized access to internal files.

What is CVE-2021-29447?

WordPress, an open-source CMS, was susceptible to an XXE attack due to an XML parsing issue in the Media Library. Attackers exploiting this vulnerability could gain access to sensitive information within the system, making it a severe security concern.

The Impact of CVE-2021-29447

The vulnerability's impact is classified as high severity, with a CVSS base score of 7.1. It could result in unauthorized disclosure of confidential information, although integrity and availability are less affected. Successful exploitation may lead to a compromised system.

Technical Details of CVE-2021-29447

This section delves into the specifics of the vulnerability, affected systems, and the exploitation mechanism.

Vulnerability Description

The vulnerability arises from improper restriction of XML External Entity Reference (CWE-611). By exploiting the XML parsing issue in the Media Library, attackers could execute XXE attacks.

Affected Systems and Versions

WordPress versions from 5.6.0 to 5.7.0 are affected, especially when running PHP 8. Users with file upload capabilities, such as Authors, are particularly at risk.

Exploitation Mechanism

Attackers with the ability to upload files can manipulate XML files to launch XXE attacks, gaining unauthorized access to internal resources.

Mitigation and Prevention

To secure systems against CVE-2021-29447, immediate actions, as well as long-term security practices, are necessary.

Immediate Steps to Take

Update WordPress to version 5.7.1 or apply the available security patches to address the vulnerability. It is crucial to limit file upload permissions to trusted users and stay informed about security advisories.

Long-Term Security Practices

Enforce regular security audits, train users on secure practices, and keep software up to date. Implementing web application firewalls and monitoring XML inputs can also enhance security.

Patching and Updates

Maintain auto-updates enabled for WordPress to receive immediate patches and security fixes, minimizing the risk of exploitation from known vulnerabilities.