CVE-2020-35478 : Security Advisory and Response

MediaWiki before version 1.35.1 is vulnerable to XSS via BlockLogFormatter.php, potentially allowing the output of MediaWiki:blanknamespace as raw HTML with SCRIPT tags through LogFormatter::makePageLink(). This impacts MediaWiki versions 1.33.0 and later.

Understanding CVE-2020-35478

MediaWiki before version 1.35.1 is susceptible to a cross-site scripting (XSS) vulnerability that can be exploited through BlockLogFormatter.php, enabling the injection of potentially malicious scripts into the output.

What is CVE-2020-35478?

This CVE identifies a security issue in MediaWiki versions prior to 1.35.1 that allows for XSS attacks via BlockLogFormatter.php, posing a risk of executing arbitrary scripts within the context of the user's session.

The Impact of CVE-2020-35478

The vulnerability in MediaWiki versions before 1.35.1 can lead to XSS attacks, enabling threat actors to inject malicious scripts into the application, potentially compromising user data and system integrity.

Technical Details of CVE-2020-35478

MediaWiki's vulnerability to XSS attacks through BlockLogFormatter.php has the following technical implications:

Vulnerability Description

The issue arises from the potential output of MediaWiki:blanknamespace as raw HTML with SCRIPT tags via LogFormatter::makePageLink(), allowing for XSS exploitation.

Affected Systems and Versions

MediaWiki versions 1.33.0 and later are impacted by this vulnerability.

Exploitation Mechanism

The vulnerability can be exploited by crafting malicious input that triggers the execution of unauthorized scripts within the application, posing a risk to user data and system security.

Mitigation and Prevention

To address CVE-2020-35478 and enhance system security, consider the following mitigation strategies:

Immediate Steps to Take

Update MediaWiki to version 1.35.1 or later to patch the XSS vulnerability.
Implement input validation and output encoding to mitigate XSS risks.

Long-Term Security Practices

Regularly monitor and audit application code for security vulnerabilities.
Educate developers on secure coding practices to prevent XSS and other common web application security threats.

Patching and Updates

Stay informed about security advisories and promptly apply patches and updates to mitigate known vulnerabilities in software components.