CVE-2021-43045
📋 TL;DR
This vulnerability in Apache Avro's .NET SDK allows attackers to cause denial-of-service by forcing excessive resource allocation. It affects .NET applications using Apache Avro version 1.10.2 and earlier. The issue is resolved in version 1.11.0.
💻 Affected Systems
- Apache Avro .NET SDK
📦 What is this software?
Avro by Apache
⚠️ Risk & Real-World Impact
Worst Case
Complete service unavailability due to resource exhaustion, potentially affecting multiple dependent services.
Likely Case
Degraded performance or temporary service disruption for affected applications.
If Mitigated
Minimal impact with proper input validation and resource limits in place.
🎯 Exploit Status
Exploitation requires ability to send malicious Avro data to vulnerable applications.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.11.0
Vendor Advisory: https://lists.apache.org/thread/5fttw9vk6gd2p3b846nox7hcj5469xfd
Restart Required: Yes
Instructions:
1. Update Apache Avro NuGet package to version 1.11.0 or later. 2. Rebuild and redeploy affected applications. 3. Restart application services.
🔧 Temporary Workarounds
Input validation and size limits
allImplement strict input validation and size limits on Avro data processing
Resource monitoring and throttling
allMonitor resource usage and implement throttling mechanisms
🧯 If You Can't Patch
- Implement strict input validation and size limits on all Avro data processing
- Deploy resource monitoring with automatic alerting for abnormal resource consumption
🔍 How to Verify
Check if Vulnerable:
Check NuGet package references for Apache.Avro version <= 1.10.2Check Version:
dotnet list package Apache.AvroVerify Fix Applied:
Verify Apache.Avro package version is >= 1.11.0 in project dependencies📡 Detection & Monitoring
Log Indicators:
- Unusually high memory or CPU usage during Avro processing
- Failed Avro parsing attempts with large payloads
Network Indicators:
- Large Avro payloads being sent to applications
- Repeated Avro data submissions
SIEM Query:
source="application_logs" AND ("Avro" OR "Apache.Avro") AND (memory_usage > threshold OR cpu_usage > threshold)