CVE-2021-30156 Explained : Impact and Mitigation

MediaWiki versions before 1.31.12 and 1.32.x through 1.35.x before 1.35.2 are affected by CVE-2021-30156. The vulnerability allows 'Special:Contributions' to reveal the presence of a hidden user.

Understanding CVE-2021-30156

This section delves into the details of CVE-2021-30156.

What is CVE-2021-30156?

CVE-2021-30156 is a vulnerability found in MediaWiki versions prior to 1.31.12 and 1.32.x through 1.35.x before 1.35.2. It enables the disclosure of a hidden user through 'Special:Contributions'.

The Impact of CVE-2021-30156

The exploitation of this vulnerability could lead to the unintended exposure of the existence of users who are meant to be hidden within the system.

Technical Details of CVE-2021-30156

This section covers the technical aspects of CVE-2021-30156.

Vulnerability Description

The flaw in MediaWiki versions allowed the 'Special:Contributions' feature to inadvertently expose the presence of concealed users.

Affected Systems and Versions

MediaWiki versions before 1.31.12 and 1.35.2 are impacted by this vulnerability.

Exploitation Mechanism

By utilizing the 'Special:Contributions' feature, an attacker could determine the presence of hidden users in the system.

Mitigation and Prevention

To protect systems from CVE-2021-30156, follow the steps outlined below.

Immediate Steps to Take

Update MediaWiki to version 1.35.2 or newer to mitigate the vulnerability. Additionally, restrict access to 'Special:Contributions' if necessary.

Long-Term Security Practices

Regularly update software to the latest versions and educate users on best security practices to prevent similar incidents.

Patching and Updates

Stay informed about security patches released by MediaWiki and promptly apply updates to ensure protection against known vulnerabilities.