CVE-2026-22858
📋 TL;DR
This CVE describes a global buffer overflow vulnerability in FreeRDP's Base64 decoding implementation. On Arm/AArch64 architectures, signedness issues allow non-ASCII bytes to bypass range checks, leading to out-of-bounds memory access. Any system running vulnerable FreeRDP versions on Arm/AArch64 hardware is affected.
💻 Affected Systems
- FreeRDP
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Application crash (denial of service) or memory corruption leading to information disclosure.
If Mitigated
Limited impact with proper network segmentation and exploit mitigations like ASLR.
🎯 Exploit Status
Exploitation requires sending specially crafted Base64 data to FreeRDP, which could be done via RDP connections or other FreeRDP integrations.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.20.1
Vendor Advisory: https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-qmqf-m84q-x896
Restart Required: Yes
Instructions:
1. Download FreeRDP 3.20.1 from official repository. 2. Stop all FreeRDP services. 3. Install/upgrade to version 3.20.1. 4. Restart services.
🔧 Temporary Workarounds
Disable FreeRDP services
linuxTemporarily disable FreeRDP services if patching isn't immediately possible.
sudo systemctl stop freerdp
sudo systemctl disable freerdp
Network segmentation
allRestrict RDP/FreeRDP traffic to trusted networks only.
🧯 If You Can't Patch
- Implement strict network access controls to limit FreeRDP exposure
- Deploy exploit mitigation technologies (ASLR, DEP, stack canaries)
🔍 How to Verify
Check if Vulnerable:
Check FreeRDP version: xfreerdp --version or dpkg -l freerdp2Check Version:
xfreerdp --versionVerify Fix Applied:
Verify version is 3.20.1 or higher: xfreerdp --version | grep -q '3.20.1'📡 Detection & Monitoring
Log Indicators:
- FreeRDP crash logs
- segmentation fault errors in system logs
- unexpected process termination
Network Indicators:
- Unusual RDP connection patterns
- malformed Base64 data in network traffic
SIEM Query:
source="*freerdp*" AND ("segmentation fault" OR "SIGSEGV" OR "buffer overflow")