CVE-2021-31410
📋 TL;DR
This vulnerability in Vaadin Designer allows remote attackers to access project source files through specially crafted HTTP requests due to overly permissive frontend resource server configuration. It affects organizations using Vaadin Designer versions 4.3.0 through 4.6.3 for web application development.
💻 Affected Systems
- Vaadin Designer
📦 What is this software?
Designer by Vaadin
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal intellectual property, extract sensitive business logic, credentials, or API keys embedded in source code, potentially leading to further system compromise.
Likely Case
Source code theft exposing proprietary application logic, configuration files, and potentially embedded secrets that could facilitate additional attacks.
If Mitigated
Limited exposure with proper network segmentation and access controls preventing external attackers from reaching vulnerable instances.
🎯 Exploit Status
Exploitation requires network access to the vulnerable Vaadin Designer instance and knowledge of HTTP request crafting.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.6.4
Vendor Advisory: https://vaadin.com/security/cve-2021-31410
Restart Required: Yes
Instructions:
1. Upgrade Vaadin Designer to version 4.6.4 or later. 2. Stop the current Vaadin Designer instance. 3. Install the updated version. 4. Restart Vaadin Designer.
🔧 Temporary Workarounds
Network Isolation
allRestrict network access to Vaadin Designer instances to trusted development networks only.
Use firewall rules to block external access to Vaadin Designer ports (default 9998)
Access Control
allImplement authentication or IP whitelisting for Vaadin Designer access.
Configure reverse proxy with authentication (e.g., nginx, Apache) in front of Vaadin Designer
🧯 If You Can't Patch
- Isolate Vaadin Designer instances on internal development networks with no internet exposure.
- Implement strict network access controls and monitor for unusual HTTP requests to Vaadin Designer endpoints.
🔍 How to Verify
Check if Vulnerable:
Check Vaadin Designer version via the application interface or configuration files. Versions 4.3.0-4.6.3 are vulnerable.Check Version:
Check the Vaadin Designer application interface or configuration files for version information.Verify Fix Applied:
Confirm version is 4.6.4 or later and test that source files cannot be accessed via HTTP requests to frontend resources.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP GET requests to Vaadin Designer frontend resource paths, especially attempts to access source files
Network Indicators:
- HTTP traffic to Vaadin Designer ports (default 9998) from untrusted sources
SIEM Query:
source="vaadin-designer" AND (http_method="GET" AND uri CONTAINS "/frontend/")