MaxKB AI Assistant: Unauthenticated Users Can Hijack Sessions and Steal Data

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5.1

MaxKB AI Assistant: Unauthenticated Users Can Hijack Sessions and Steal Data

CVE-2026-39425

Summary

Versions 2.7.1 and below of MaxKB's AI assistant software contain a security flaw that lets malicious users inject code into the app's chat interface. This can allow them to take control of other users' sessions, delete important data, and access sensitive information. To fix this, update to version 2.8.0 or later.

Original title

Original description

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain a Stored Cross-Site Scripting (XSS) vulnerability that allows authenticated users to inject arbitrary HTML and JavaScript into the Application prologue (Opening Remarks) field by wrapping malicious payloads in <html_rander> tags. The backend fails to sanitize or encode HTML entities in the prologue field when applications are created or updated via the /admin/api/workspace/{workspace_id}/application endpoint, storing the raw payload directly in the database. The frontend then renders this content using an innerHTML-equivalent mechanism, trusting <html_rander>-wrapped content to be safe, which enables persistent DOM-based Stored XSS execution against any visitor who opens the affected chatbot interface. Exploitation can lead to session hijacking, unauthorized actions performed on behalf of victims (such as deleting workspaces or applications), and sensitive data exposure. This issue has been fixed in version 2.8.0.

nvd CVSS4.0 5.1

Vulnerability type

CWE-80 Basic XSS

Published: 14 Apr 2026 · Updated: 15 Apr 2026 · First seen: 14 Apr 2026