CVE-2026-22856
📋 TL;DR
This CVE describes a race condition vulnerability in FreeRDP's serial channel IRP thread tracking that allows heap use-after-free. Attackers could exploit this to potentially execute arbitrary code or cause denial of service. Anyone using FreeRDP versions prior to 3.20.1 is affected.
💻 Affected Systems
- FreeRDP
📦 What is this software?
Freerdp by Freerdp
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment
Likely Case
Application crash or denial of service, potentially leading to remote desktop session disruption
If Mitigated
Limited impact with proper network segmentation and exploit mitigations in place
🎯 Exploit Status
Exploitation requires race condition timing and knowledge of heap layout
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.20.1
Vendor Advisory: https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-w842-c386-fxhv
Restart Required: Yes
Instructions:
1. Download FreeRDP 3.20.1 from official repository
2. Stop all FreeRDP services
3. Install the new version
4. Restart services
🔧 Temporary Workarounds
Disable Serial Channel
allDisable serial channel functionality if not required
Add /serial to FreeRDP connection parameters to disable serial channel
🧯 If You Can't Patch
- Implement network segmentation to isolate FreeRDP servers
- Apply exploit mitigations like ASLR and DEP if available
🔍 How to Verify
Check if Vulnerable:
Check FreeRDP version with 'xfreerdp --version' or equivalentCheck Version:
xfreerdp --versionVerify Fix Applied:
Verify version is 3.20.1 or higher after update📡 Detection & Monitoring
Log Indicators:
- FreeRDP process crashes
- Unexpected memory access errors in system logs
Network Indicators:
- Unusual RDP connection patterns
- Multiple failed connection attempts
SIEM Query:
process_name:"freerdp" AND (event_type:crash OR memory_violation)