CVE-2019-15683
📋 TL;DR
This vulnerability allows authenticated attackers to trigger a stack buffer overflow in TurboVNC server versions prior to commit cea98166008301e614e0d36776bf9435a536136e. Successful exploitation could lead to remote code execution on the VNC server. Organizations running vulnerable TurboVNC servers with network connectivity are affected.
💻 Affected Systems
- TurboVNC
📦 What is this software?
Turbovnc by Turbovnc
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with server privileges leading to complete system compromise, lateral movement, and data exfiltration.
Likely Case
Server crash (denial of service) or limited code execution depending on exploit reliability and system protections.
If Mitigated
Denial of service from failed exploitation attempts or blocked network access.
🎯 Exploit Status
Requires authentication but stack canary protection is absent, making exploitation more feasible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Commit cea98166008301e614e0d36776bf9435a536136e and later
Vendor Advisory: https://github.com/TurboVNC/turbovnc/commit/cea98166008301e614e0d36776bf9435a536136e
Restart Required: Yes
Instructions:
1. Update TurboVNC to version containing commit cea98166008301e614e0d36776bf9435a536136e or later. 2. Restart TurboVNC server service. 3. Verify the fix by checking version/commit hash.
🔧 Temporary Workarounds
Network Segmentation
linuxRestrict network access to TurboVNC server to trusted IP addresses only.
iptables -A INPUT -p tcp --dport 5900 -s trusted_ip_range -j ACCEPT
iptables -A INPUT -p tcp --dport 5900 -j DROP
Disable TurboVNC Server
linuxTemporarily disable TurboVNC server until patching is possible.
systemctl stop turbovnc
systemctl disable turbovnc
🧯 If You Can't Patch
- Implement strict network access controls to limit VNC server exposure
- Use application allowlisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check TurboVNC version or commit hash against vulnerable range (prior to cea98166008301e614e0d36776bf9435a536136e).Check Version:
vncserver -version or check git commit hash in source installationVerify Fix Applied:
Verify TurboVNC is running commit cea98166008301e614e0d36776bf9435a536136e or later.📡 Detection & Monitoring
Log Indicators:
- TurboVNC server crash logs
- Unexpected process termination
- Authentication logs showing exploitation attempts
Network Indicators:
- Unusual network traffic patterns to VNC port
- Multiple failed authentication attempts followed by buffer overflow patterns
SIEM Query:
source="turbovnc.log" AND ("segmentation fault" OR "buffer overflow" OR "stack smashing")