CVE-2025-50054
📋 TL;DR
A buffer overflow vulnerability in OpenVPN's ovpn-dco-win kernel driver allows local user processes to send oversized control messages, causing system crashes. This affects OpenVPN installations using the Data Channel Offload driver on Windows systems. Only local authenticated users can trigger this vulnerability.
💻 Affected Systems
- OpenVPN with ovpn-dco-win driver
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Local denial of service causing system crashes or kernel panics, potentially leading to service disruption and data loss.
Likely Case
Local user causes system instability or crashes OpenVPN service, disrupting VPN connectivity.
If Mitigated
Minimal impact with proper access controls limiting local user privileges.
🎯 Exploit Status
Exploitation requires local user access and ability to send control messages to the kernel driver.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: OpenVPN 2.7 alpha2 (released June 19, 2025) includes fixes
Vendor Advisory: https://community.openvpn.net/Security%20Announcements/CVE-2025-50054
Restart Required: Yes
Instructions:
1. Download OpenVPN 2.7 alpha2 or later from OpenVPN community downloads. 2. Install the updated version. 3. Restart the OpenVPN service or reboot the system.
🔧 Temporary Workarounds
Disable ovpn-dco-win driver
windowsTemporarily disable the vulnerable Data Channel Offload driver
netsh interface set interface "OpenVPN Data Channel Offload" admin=disabled
Restrict local user privileges
windowsLimit which local users can interact with OpenVPN services
🧯 If You Can't Patch
- Implement strict access controls to limit local user privileges on affected systems
- Monitor for system crashes or OpenVPN service disruptions and implement compensating network controls
🔍 How to Verify
Check if Vulnerable:
Check OpenVPN version and ovpn-dco-win driver version. Vulnerable if using ovpn-dco-win <=1.3.0 or <=2.5.8.Check Version:
openvpn --versionVerify Fix Applied:
Verify OpenVPN version is 2.7 alpha2 or later and ovpn-dco-win driver is updated.📡 Detection & Monitoring
Log Indicators:
- System crash logs
- OpenVPN service failure events
- Kernel panic events in Windows Event Viewer
Network Indicators:
- Sudden VPN connection drops
- Unusual local process interactions with OpenVPN
SIEM Query:
EventID=1001 OR EventID=41 OR Source="OpenVPN" AND (EventID=6008 OR EventID=6009)