CVE-2026-0671 in UploadWizard Extension
Summary
by MITRE • 01/08/2026
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Wikimedia Foundation MediaWiki - UploadWizard extension allows Cross-Site Scripting (XSS).This issue affects MediaWiki - UploadWizard extension: 1.45, 1.44, 1.43, 1.39.
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Analysis
by VulDB Data Team • 01/09/2026
The vulnerability identified as CVE-2026-0671 represents a critical improper neutralization of input during web page generation, specifically manifesting as a cross-site scripting vulnerability within the Wikimedia Foundation MediaWiki UploadWizard extension. This flaw exists in multiple versions including 1.45, 1.44, 1.43, and 1.39, indicating a widespread impact across the MediaWiki ecosystem. The UploadWizard extension serves as a crucial component for media uploads within Wikimedia projects, making this vulnerability particularly concerning given its potential to compromise user interactions and data integrity across numerous wiki platforms. The vulnerability stems from inadequate sanitization of user-supplied input parameters that are subsequently rendered in web page contexts without proper escaping or encoding mechanisms.
The technical exploitation of this XSS vulnerability occurs when malicious input is processed through the UploadWizard extension and subsequently displayed in generated web pages without appropriate neutralization. Attackers can inject malicious scripts into file names, descriptions, or other user-controllable fields within the upload wizard interface. These scripts execute in the context of other users' browsers when they view the affected media items or related pages, creating a persistent threat vector. The vulnerability maps directly to CWE-79, which specifically addresses Cross-site Scripting flaws in web applications, where insufficient input validation and output encoding creates opportunities for attackers to inject malicious code. This weakness allows for potential session hijacking, data theft, and malicious redirection attacks that can compromise user privacy and system integrity.
The operational impact of this vulnerability extends beyond simple script execution, as it can facilitate more sophisticated attacks within the Wikimedia ecosystem. When exploited, the XSS vulnerability enables attackers to manipulate user sessions, steal authentication tokens, or redirect users to malicious domains. The UploadWizard extension's integration with MediaWiki's core functionality means that a successful exploitation could affect not only individual user experiences but potentially compromise entire wiki communities. The vulnerability's presence in multiple versions suggests that a significant number of Wikimedia projects remain exposed, creating a substantial attack surface that could be leveraged for coordinated attacks across various wiki platforms. Security researchers have identified that the affected versions lack proper HTML escaping mechanisms when processing user input, allowing attackers to inject script tags or other malicious payloads that persistently execute in user browsers.
Mitigation strategies for CVE-2026-0671 should prioritize immediate version updates to patched releases of the MediaWiki UploadWizard extension, with particular emphasis on upgrading to versions that implement proper input sanitization and output encoding. Organizations maintaining MediaWiki installations should implement comprehensive input validation at multiple layers, ensuring that all user-supplied data undergoes strict sanitization before being stored or rendered in web contexts. The implementation of Content Security Policy headers can provide additional protection against script execution, while proper HTML escaping mechanisms should be enforced throughout the application's rendering pipeline. Security teams should also consider implementing web application firewalls to detect and block suspicious input patterns, and conduct regular security audits of MediaWiki extensions to identify similar vulnerabilities. The ATT&CK framework categorizes this vulnerability under T1566, specifically targeting the exploitation of web application vulnerabilities, making it essential for organizations to maintain proactive security monitoring and remediation procedures. Additionally, user education regarding the risks of uploading untrusted content and the importance of verifying file metadata can help reduce the likelihood of successful exploitation.