CVE-2020-27620 : What You Need to Know

The Cosmos Skin for MediaWiki through version 1.35.0 is vulnerable to stored XSS due to improper escaping of MediaWiki messages.

Understanding CVE-2020-27620

This CVE involves a security issue in the Cosmos Skin for MediaWiki that allows for stored cross-site scripting attacks.

What is CVE-2020-27620?

The vulnerability in the Cosmos Skin for MediaWiki up to version 1.35.0 enables attackers to execute malicious scripts by manipulating MediaWiki messages that were not adequately escaped.

The Impact of CVE-2020-27620

The stored XSS vulnerability in the Cosmos Skin for MediaWiki can lead to unauthorized script execution, potentially compromising user data and system integrity.

Technical Details of CVE-2020-27620

The technical aspects of the vulnerability in the Cosmos Skin for MediaWiki.

Vulnerability Description

The issue arises from the lack of proper escaping of MediaWiki messages, specifically related to wfMessage and Html::rawElement, as demonstrated by CosmosSocialProfile::getUserGroups.

Affected Systems and Versions

Product: Cosmos Skin for MediaWiki
Versions affected: up to 1.35.0

Exploitation Mechanism

The vulnerability can be exploited by injecting malicious scripts into MediaWiki messages, taking advantage of the lack of proper escaping mechanisms.

Mitigation and Prevention

Steps to mitigate and prevent the exploitation of CVE-2020-27620.

Immediate Steps to Take

Update the Cosmos Skin for MediaWiki to the latest version that includes a patch for the XSS vulnerability.
Implement input validation and output encoding to prevent script injection.

Long-Term Security Practices

Regularly monitor and audit MediaWiki extensions for security vulnerabilities.
Educate developers on secure coding practices to prevent XSS attacks.

Patching and Updates

Apply security patches promptly to address known vulnerabilities and enhance system security.