CVE-2020-36320
📋 TL;DR
This vulnerability allows attackers to cause denial of service through resource exhaustion by submitting specially crafted email addresses that trigger inefficient regular expression processing in Vaadin's EmailValidator. It affects all applications using Vaadin framework versions 7.0.0 through 7.7.21 that perform email validation.
💻 Affected Systems
- Vaadin Framework
📦 What is this software?
Vaadin by Vaadin
⚠️ Risk & Real-World Impact
Worst Case
Complete application unavailability due to CPU exhaustion, potentially affecting all users and requiring server restart.
Likely Case
Degraded application performance, increased response times, and potential service disruption for some users.
If Mitigated
Minimal impact with proper input validation, rate limiting, and monitoring in place.
🎯 Exploit Status
Exploitation requires no authentication and can be performed with simple HTTP requests containing malicious email patterns.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.7.22
Vendor Advisory: https://vaadin.com/security/cve-2020-36320
Restart Required: Yes
Instructions:
1. Update Vaadin dependency to version 7.7.22 or later in your project's build configuration (Maven/Gradle). 2. Rebuild and redeploy your application. 3. Restart application servers.
🔧 Temporary Workarounds
Input validation bypass
allDisable or bypass the vulnerable EmailValidator by implementing custom email validation
Implement custom validation logic that doesn't use the vulnerable regex pattern
Rate limiting
allImplement request rate limiting to prevent mass exploitation
Configure web server or application rate limiting rules
🧯 If You Can't Patch
- Implement WAF rules to block requests with suspicious email patterns
- Deploy monitoring for abnormal CPU usage patterns and implement alerting
🔍 How to Verify
Check if Vulnerable:
Check your project's pom.xml or build.gradle for Vaadin version 7.0.0-7.7.21Check Version:
mvn dependency:tree | grep vaadin-server OR check build.gradle dependenciesVerify Fix Applied:
Verify Vaadin version is 7.7.22 or higher after update📡 Detection & Monitoring
Log Indicators:
- Multiple failed validation attempts with unusual email patterns
- Increased error rates in validation logs
Network Indicators:
- High volume of requests to validation endpoints
- Requests containing complex regex patterns in email fields
SIEM Query:
source="application_logs" AND (message="*EmailValidator*" OR message="*validation*error*") AND count > threshold