CVE-2026-103439
Received Received - Intake

Basic XSS in MediaWiki Wikibase Extension

Publication date: 2026-09-30

Last updated on: 2026-09-30

Assigner: wikimedia-foundation

Description
Improper neutralization of Script-Related HTML tags in a web page (basic XSS) vulnerability in The Wikimedia Foundation MediaWiki Wikbase extension allows Cross-Site Scripting (XSS). This issue affects MediaWiki Wikbase extension: 1.46, 1.45, and 1.43.

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Meta Information

Published
2026-09-30
Last Modified
2026-09-30
Generated
2026-09-30
AI Q&A
2026-09-30
EPSS Evaluated
N/A
NVD
CVE-2026-103439
EUVD
EUVD-2026-90211

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
the_wikimedia_foundation mediawiki_wikbase_extension 1.46
the_wikimedia_foundation mediawiki_wikbase_extension 1.45
the_wikimedia_foundation mediawiki_wikbase_extension 1.43

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-80 The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.

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Executive Summary

This is a basic Cross-Site Scripting (XSS) vulnerability caused by improper neutralization of Script-Related HTML tags in the Wikimedia Foundation MediaWiki Wikbase extension. It allows attackers to inject malicious scripts into web pages viewed by other users.

Impact Analysis

If exploited, this vulnerability could allow attackers to execute arbitrary scripts in the context of a user's browser session. This may lead to theft of session cookies, account hijacking, or unauthorized actions on behalf of the user.

Compliance Impact

This XSS vulnerability could potentially lead to unauthorized access to personal data, violating GDPR's data protection principles. For HIPAA, it may compromise protected health information if exploited in healthcare-related MediaWiki deployments.

Mitigation Strategies

Update the MediaWiki Wikbase extension to a patched version if available. Review and sanitize user inputs to prevent XSS attacks. Monitor web application logs for suspicious activity.

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