CVE-2025-6596 in Vector
Summary
by MITRE • 02/03/2026
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Wikimedia Foundation Vector. This vulnerability is associated with program files resources/skins.Vector.Js/portlets.Js, resources/skins.Vector.Legacy.Js/portlets.Js.
This issue affects Vector: from >= 1.40.0 before 1.42.7, 1.43.2, 1.44.0.
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Analysis
by VulDB Data Team • 02/04/2026
This vulnerability represents a critical cross-site scripting flaw in the Wikimedia Foundation Vector skin implementation that allows remote attackers to inject malicious scripts into web pages. The vulnerability specifically resides in the portlets.js files within the Vector skin's JavaScript resources, where input validation and sanitization mechanisms fail to properly neutralize user-supplied data during web page generation processes. The flaw affects multiple versions of the Vector skin including releases from 1.40.0 through 1.42.6, 1.43.1, and 1.43.0, creating a substantial attack surface for malicious actors targeting Wikimedia projects. This type of vulnerability falls under CWE-79 which defines improper neutralization of input during web page generation as a primary weakness category for cross-site scripting attacks.
The technical execution of this vulnerability occurs when the Vector skin processes user input through the portlets.js JavaScript modules without adequate sanitization of potentially malicious content. When users interact with web pages utilizing the affected Vector skin versions, the application fails to properly escape or filter special characters that could be interpreted as executable script code by web browsers. This allows attackers to inject malicious payloads that execute in the context of other users' browsers, potentially leading to session hijacking, credential theft, or arbitrary code execution within the victim's browser environment. The vulnerability specifically impacts the legacy and modern implementations of the Vector skin, indicating a widespread issue across different code repositories that handle similar functionality. Attackers can exploit this by crafting malicious input that gets rendered in the web interface, leveraging the inherent trust relationship between the browser and the web application.
The operational impact of this vulnerability extends beyond simple script injection, as it can compromise the integrity and confidentiality of user sessions across Wikimedia Foundation platforms. When exploited, the vulnerability enables attackers to manipulate web page content, redirect users to malicious sites, or steal sensitive information from authenticated users. The affected versions span multiple major releases, suggesting that this vulnerability has been present for an extended period and could have affected numerous Wikimedia projects including Wikipedia and relatedency projects. The nature of the flaw means that any user interaction with pages utilizing the affected Vector skin components could potentially expose them to attack vectors, creating a broad threat surface that affects the entire Wikimedia ecosystem. This vulnerability directly aligns with ATT&CK technique T1531 which focuses on establishing persistence through web shell creation and T1059 which covers command and scripting interpreters for execution.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected Vector skin versions to the latest secure releases. Organizations should implement comprehensive input validation and output encoding mechanisms throughout the application stack to prevent similar issues from occurring in other components. The fix should include proper sanitization of all user-supplied data before rendering in web pages, with special attention to JavaScript escape sequences and HTML entity encoding. Security teams should also consider implementing content security policies to limit script execution capabilities and monitor for suspicious user behavior patterns that might indicate exploitation attempts. Additionally, regular security assessments of web application components should include thorough testing for cross-site scripting vulnerabilities in all JavaScript modules, particularly those handling user input or dynamic content generation. The remediation process should follow secure coding practices aligned with OWASP Top Ten recommendations and include thorough regression testing to ensure that security fixes do not introduce new functionality issues.