CVE-2021-39186 Explained : Impact and Mitigation

GlobalNewFiles, a MediaWiki extension by Miraheze, is vulnerable to stored XSS due to improper input validation prior to commit cee254e1b. Learn about the impact, technical details, and mitigation steps.

Understanding CVE-2021-39186

This CVE involves the GlobalNewFiles MediaWiki extension by Miraheze, where a stored XSS vulnerability exists.

What is CVE-2021-39186?

GlobalNewFiles, maintained by Miraheze, had a vulnerability where the username column of the special page was susceptible to stored XSS.

The Impact of CVE-2021-39186

The CVSS score for this vulnerability is 4.3, with medium severity. Attack complexity is low, requiring user interaction and no privileges. The integrity impact is low with no confidentiality impact.

Technical Details of CVE-2021-39186

This section covers the specifics of the vulnerability.

Vulnerability Description

Prior to commit cee254e1, the username column in the GlobalNewFiles special page was vulnerable to stored XSS. The said commit provides a patch for the issue.

Affected Systems and Versions

Product: GlobalNewFiles
Vendor: Miraheze
Versions Affected: All versions prior to commit cee254e1

Exploitation Mechanism

By inserting malicious characters like <,> in account names, attackers can execute XSS attacks.

Mitigation and Prevention

Here are steps to mitigate the vulnerability in GlobalNewFiles.

Immediate Steps to Take

Apply the patch from commit cee254e1 or later.
Avoid using potentially harmful characters in usernames.

Long-Term Security Practices

Conduct regular security audits for MediaWiki extensions.
Educate users on secure username practices to prevent XSS.

Patching and Updates

Regularly update GlobalNewFiles to the latest version containing security patches.