CVE-2025-13751
📋 TL;DR
A local denial-of-service vulnerability in OpenVPN's Windows interactive service agent allows authenticated local users to crash the service by triggering an error. This affects OpenVPN versions 2.5.0 through 2.6.16 and 2.7_alpha1 through 2.7_rc2 on Windows systems.
💻 Affected Systems
- OpenVPN
📦 What is this software?
Openvpn by Openvpn
Openvpn by Openvpn
Openvpn by Openvpn
Openvpn by Openvpn
Openvpn by Openvpn
Openvpn by Openvpn
Openvpn by Openvpn
Openvpn by Openvpn
Openvpn by Openvpn
⚠️ Risk & Real-World Impact
Worst Case
Local authenticated attacker crashes OpenVPN service, disrupting VPN connectivity for all users until service restart.
Likely Case
Malicious local user or malware with local access causes temporary VPN service disruption.
If Mitigated
Minimal impact with proper access controls limiting local user privileges.
🎯 Exploit Status
Requires local authenticated access to Windows system. No public exploit code available at disclosure time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: OpenVPN 2.6.17 and 2.7_rc3
Vendor Advisory: https://community.openvpn.net/Security%20Announcements/CVE-2025-13751
Restart Required: Yes
Instructions:
1. Download OpenVPN 2.6.17 or 2.7_rc3 from official sources. 2. Stop OpenVPN service. 3. Install updated version. 4. Restart OpenVPN service.
🔧 Temporary Workarounds
Restrict local user access
windowsLimit local user privileges to prevent authenticated exploitation
Use service hardening
windowsConfigure OpenVPN service to run with minimal privileges
sc.exe config OpenVPNService obj= "NT AUTHORITY\LocalService"
🧯 If You Can't Patch
- Implement strict access controls to limit which local users can interact with OpenVPN service
- Monitor for service crashes and implement automated restart mechanisms
🔍 How to Verify
Check if Vulnerable:
Check OpenVPN version: openvpn --version. If version is between 2.5.0-2.6.16 or 2.7_alpha1-2.7_rc2 on Windows, system is vulnerable.Check Version:
openvpn --versionVerify Fix Applied:
Verify version is 2.6.17 or higher, or 2.7_rc3 or higher. Check service stability after update.📡 Detection & Monitoring
Log Indicators:
- OpenVPN service crash events in Windows Event Log
- Unexpected service termination logs
Network Indicators:
- Sudden VPN connection drops for multiple users
- Failed VPN authentication attempts
SIEM Query:
EventID=7034 OR EventID=7031 OR EventID=7023 AND ServiceName="OpenVPN"