CVE-2025-63211
📋 TL;DR
A stored cross-site scripting (XSS) vulnerability in bridgetech VBC Server & Element Manager allows attackers to inject malicious scripts via the addName parameter in the /vbc/core/userSetupDoc/userSetupDoc endpoint. When exploited, this can enable arbitrary code execution in users' browsers. Organizations using affected firmware versions 6.5.0-9 through 6.5.0-10 are vulnerable.
💻 Affected Systems
- bridgetech VBC Server
- bridgetech Element Manager
📦 What is this software?
Vbc Server by Bridgetech
Vbc Server by Bridgetech
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator credentials, hijack user sessions, redirect users to malicious sites, or perform actions on behalf of authenticated users, potentially leading to full system compromise.
Likely Case
Attackers inject malicious JavaScript that steals session cookies or credentials when administrators or users access the vulnerable interface, leading to unauthorized access.
If Mitigated
With proper input validation and output encoding, the malicious payload would be neutralized, preventing script execution while maintaining functionality.
🎯 Exploit Status
Exploitation requires access to the vulnerable endpoint, which typically requires authentication. The GitHub repository contains research details about the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://bridgetech.tv/
Restart Required: No
Instructions:
1. Monitor bridgetech.tv for security advisories. 2. Apply firmware updates when available. 3. Verify the fix by testing the addName parameter with XSS payloads.
🔧 Temporary Workarounds
Input Validation and Sanitization
allImplement server-side validation to reject or sanitize malicious input in the addName parameter.
Not applicable - requires code changes
Web Application Firewall (WAF)
allDeploy a WAF with XSS protection rules to block malicious requests to the vulnerable endpoint.
Not applicable - configuration dependent
🧯 If You Can't Patch
- Restrict network access to the VBC Server/Element Manager web interface to trusted IP addresses only.
- Implement Content Security Policy (CSP) headers to mitigate the impact of successful XSS attacks.
🔍 How to Verify
Check if Vulnerable:
Test the /vbc/core/userSetupDoc/userSetupDoc endpoint with a benign XSS payload in the addName parameter (e.g., <script>alert('test')</script>) and check if it executes when the page is viewed.Check Version:
Check the firmware version in the web interface or via system commands specific to the device (exact command varies by deployment).Verify Fix Applied:
After applying mitigations, repeat the vulnerability test to ensure XSS payloads are properly sanitized or blocked.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /vbc/core/userSetupDoc/userSetupDoc with script tags or JavaScript in parameters
- Multiple failed login attempts followed by successful access to user management
Network Indicators:
- HTTP requests containing <script>, javascript:, or other XSS payloads in the addName parameter
SIEM Query:
source="web_logs" AND uri="/vbc/core/userSetupDoc/userSetupDoc" AND (param="*<script>*" OR param="*javascript:*")🔗 References
- https://bridgetech.tv/
- https://github.com/shiky8/my--cve-vulnerability-research/tree/main/CVE-2025-63211_bridgetech%20VBC%20Server%20and%20Element%20Manager%20Stored%20%20xss
- https://github.com/shiky8/my--cve-vulnerability-research/tree/main/CVE-2025-63211_bridgetech%20VBC%20Server%20and%20Element%20Manager%20Stored%20%20xss
