CVE-2026-25200: MagicInfo9 Server Stored XSS Vulnerability

CVE-2026-25200 Overview

A critical vulnerability has been identified in Samsung MagicINFO 9 Server that allows authorized users to upload HTML files without proper authentication validation. This unrestricted file upload flaw (CWE-434) leads to Stored Cross-Site Scripting (XSS), which can result in complete account takeover of administrative and user sessions.

Samsung MagicINFO 9 Server is a widely deployed digital signage management platform used by enterprises to manage content across displays and kiosks. The vulnerability's network-accessible attack vector combined with no required user interaction makes it particularly dangerous for organizations relying on this platform.

Critical Impact

Attackers can leverage this stored XSS vulnerability to hijack administrator sessions, steal credentials, and gain full control over the digital signage infrastructure, potentially affecting all connected displays and systems.

Affected Products

• Samsung MagicINFO 9 Server versions prior to 21.1090.1

Discovery Timeline

• 2026-02-02 - CVE-2026-25200 published to NVD
• 2026-02-03 - Last updated in NVD database

Technical Details for CVE-2026-25200

Vulnerability Analysis

This vulnerability stems from an Unrestricted Upload of File with Dangerous Type (CWE-434) within the MagicINFO 9 Server application. The server fails to properly validate and restrict file types during the upload process, allowing authorized users to upload HTML files containing malicious JavaScript payloads.

Once uploaded, these HTML files are stored on the server and served to other users without proper sanitization. When an administrator or another user views the uploaded content, the malicious JavaScript executes within their browser context, enabling session hijacking, credential theft, and other malicious actions.

The attack is particularly severe because it can be exploited remotely over the network without requiring user interaction beyond the initial page load. The stored nature of the XSS ensures persistence, meaning the malicious payload remains active until the offending file is removed.

Root Cause

The root cause of CVE-2026-25200 lies in insufficient input validation and file type restrictions in the MagicINFO 9 Server's file upload functionality. The application fails to:

1. Properly validate file extensions and MIME types before accepting uploads
2. Sanitize HTML content to remove potentially malicious script elements
3. Implement Content Security Policy (CSP) headers that would prevent inline script execution
4. Apply authentication checks to validate that the user has appropriate permissions for uploading certain file types

Attack Vector

The attack vector for this vulnerability is network-based. An attacker with authorized access to the MagicINFO 9 Server can craft a malicious HTML file containing JavaScript that captures session tokens, cookies, or credentials. When this file is uploaded to the server and subsequently accessed by other users (particularly administrators), the embedded script executes in the victim's browser session.

The malicious script could redirect authentication tokens to attacker-controlled servers, create new administrative accounts, modify display content across all connected digital signage, or serve as a pivot point for further network intrusion. The vulnerability effectively transforms any authorized user into a potential attack vector against higher-privileged accounts.

Detection Methods for CVE-2026-25200

Indicators of Compromise

• Unusual HTML file uploads to the MagicINFO 9 Server content directories
• HTML files containing <script> tags, javascript: URI schemes, or event handlers like onerror, onload, onclick
• Network traffic from the MagicINFO server to unexpected external domains
• Session token exfiltration attempts in server or proxy logs

Detection Strategies

• Monitor file upload endpoints for HTML, HTM, SVG, and other files capable of containing executable scripts
• Implement Web Application Firewall (WAF) rules to detect and block XSS payload patterns in uploaded content
• Review server access logs for patterns indicating session hijacking or unauthorized administrative actions
• Deploy endpoint detection tools to identify anomalous JavaScript execution in browser contexts

Monitoring Recommendations

• Enable detailed logging for all file upload activities including user identity, file type, and file hash
• Configure alerts for administrative account modifications or new account creations
• Monitor outbound network connections from the MagicINFO server for data exfiltration indicators
• Implement real-time file integrity monitoring on content storage directories

How to Mitigate CVE-2026-25200

Immediate Actions Required

• Upgrade Samsung MagicINFO 9 Server to version 21.1090.1 or later immediately
• Audit existing uploaded content for suspicious HTML files containing script elements
• Review user accounts with upload permissions and apply principle of least privilege
• Implement network segmentation to limit access to the MagicINFO management interface

Patch Information

Samsung has addressed this vulnerability in MagicINFO 9 Server version 21.1090.1. Organizations should apply this update as soon as possible to remediate the unrestricted file upload and stored XSS vulnerabilities. For detailed patch information and download links, refer to the Samsung TV Security Updates page.

Workarounds

• Restrict file upload functionality to trusted administrators only until the patch can be applied
• Implement a whitelist of allowed file extensions excluding HTML, HTM, SVG, and other scriptable formats
• Deploy a Content Security Policy (CSP) header with strict restrictions on inline scripts and external script sources
• Place the MagicINFO 9 Server behind a reverse proxy with XSS filtering capabilities

Organizations should prioritize patching as the primary remediation strategy, as workarounds may not fully address all attack scenarios and could impact legitimate functionality.