CVE-2025-66921
📋 TL;DR
This Cross-site scripting (XSS) vulnerability in Open Source Point of Sale v3.4.1 allows remote attackers to inject malicious scripts via the 'name' parameter in the Create/Update Item(s) module. Attackers can execute arbitrary JavaScript in victims' browsers, potentially stealing session cookies or performing actions as authenticated users. All users running Open Source Point of Sale v3.4.1 are affected.
💻 Affected Systems
- Open Source Point of Sale
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attacker steals administrator session cookies, gains full control of the POS system, modifies pricing, steals customer payment data, or installs backdoors.
Likely Case
Attacker steals user session cookies to gain unauthorized access, modifies inventory items, or redirects users to phishing sites.
If Mitigated
Script execution is blocked by Content Security Policy or input validation, limiting impact to minor UI disruption.
🎯 Exploit Status
Exploitation requires authenticated access to the Create/Update Item(s) module; XSS payloads are simple to craft.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://github.com/opensourcepos/opensourcepos
Restart Required: No
Instructions:
1. Monitor the official GitHub repository for security updates. 2. Apply any available patches immediately. 3. Consider upgrading to a newer version if patched version is released.
🔧 Temporary Workarounds
Input Validation and Sanitization
allImplement server-side validation to sanitize the 'name' parameter, removing or encoding HTML/JavaScript characters.
Content Security Policy (CSP)
allDeploy a strict CSP header to block inline scripts and restrict script sources to trusted domains only.
Content-Security-Policy: default-src 'self'; script-src 'self'
🧯 If You Can't Patch
- Restrict access to the POS system to trusted networks only using firewalls or VPNs.
- Implement web application firewall (WAF) rules to block XSS payloads in the 'name' parameter.
🔍 How to Verify
Check if Vulnerable:
Test by entering a basic XSS payload like <script>alert('XSS')</script> in the 'name' field of the Create/Update Item(s) module and check if it executes.Check Version:
Check the version in the admin panel or via the application's about/help section.Verify Fix Applied:
After applying fixes, retest with XSS payloads to ensure they are properly sanitized or blocked.📡 Detection & Monitoring
Log Indicators:
- Unusual length or special characters in 'name' parameter logs
- Multiple failed login attempts followed by item creation/modification
Network Indicators:
- HTTP requests with script tags or JavaScript in the 'name' parameter
- Unusual outbound connections from the POS server
SIEM Query:
source="web_logs" AND (name="*<script>*" OR name="*javascript:*")