CVE-2021-30157 : Vulnerability Insights and Analysis

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. This vulnerability exists on ChangesList special pages like Special:RecentChanges and Special:Watchlist, where some rcfilters-filter-* label messages are output in HTML unescaped, potentially leading to Cross-Site Scripting (XSS) attacks.

Understanding CVE-2021-30157

This CVE pertains to a vulnerability found in MediaWiki versions before 1.31.12 and 1.32.x through 1.35.x before 1.35.2, impacting special pages such as Special:RecentChanges and Special:Watchlist.

What is CVE-2021-30157?

The vulnerability in CVE-2021-30157 involves certain label messages being displayed in HTML unescaped manner on specific special pages in MediaWiki, potentially exposing users to XSS attacks.

The Impact of CVE-2021-30157

If exploited, this vulnerability could allow an attacker to execute malicious scripts in the context of an unsuspecting user’s browser, leading to potential data theft or unauthorized actions being performed by the attacker.

Technical Details of CVE-2021-30157

This section covers the technical aspects of the vulnerability.

Vulnerability Description

The vulnerability arises from the unescaped output of rcfilters-filter-* label messages on ChangesList special pages in affected versions of MediaWiki.

Affected Systems and Versions

MediaWiki versions before 1.31.12 and 1.32.x through 1.35.x before 1.35.2 are affected by this vulnerability.

Exploitation Mechanism

By injecting malicious scripts through the unescaped label messages on special pages, attackers can potentially exploit this vulnerability to carry out XSS attacks.

Mitigation and Prevention

It is crucial to take immediate action to mitigate the risks associated with CVE-2021-30157.

Immediate Steps to Take

Users are advised to update their MediaWiki installations to versions 1.31.12 or 1.35.2, which include fixes for this vulnerability. Additionally, users should sanitize inputs and validate outputs in their applications to prevent XSS vulnerabilities.

Long-Term Security Practices

Implementing secure coding practices, conducting regular vulnerability assessments, and staying informed about security updates for all software components are essential for maintaining a secure environment.

Patching and Updates

Users should regularly check for security advisories from MediaWiki and apply patches promptly to address known vulnerabilities and protect their systems from potential exploits.