CVE-2024-46586
📋 TL;DR
A buffer overflow vulnerability in Draytek Vigor 3910 routers allows attackers to cause Denial of Service (DoS) by sending specially crafted input to the sCloudPass parameter. This affects organizations using Draytek Vigor 3910 routers with vulnerable firmware. The vulnerability is remotely exploitable without authentication.
💻 Affected Systems
- Draytek Vigor 3910
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router crash requiring physical reboot, potential remote code execution if buffer overflow can be controlled precisely (though not confirmed in description), and extended network downtime.
Likely Case
Router becomes unresponsive requiring reboot, causing temporary network disruption for connected devices and services.
If Mitigated
If properly segmented and behind firewalls, impact limited to isolated network segment with quick recovery via reboot.
🎯 Exploit Status
Buffer overflow in web interface parameter suggests straightforward exploitation via HTTP request.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Draytek website for firmware updates
2. Download latest firmware
3. Backup router configuration
4. Upload and apply firmware update
5. Reboot router
🔧 Temporary Workarounds
Disable cloud management
allDisable sCloud or cloud management features if not required
Network segmentation
allPlace router behind firewall with restricted access to management interface
🧯 If You Can't Patch
- Implement strict firewall rules to restrict access to router management interface to trusted IPs only
- Monitor router logs for unusual HTTP requests to v2x00.cgi endpoint
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System Maintenance > Firmware InformationCheck Version:
Not applicable - check via web interfaceVerify Fix Applied:
Verify firmware version is newer than v4.3.2.6📡 Detection & Monitoring
Log Indicators:
- HTTP requests to /v2x00.cgi with long sCloudPass parameter
- Router crash/reboot events in system logs
Network Indicators:
- HTTP POST requests to router IP on port 80/443 with abnormal parameter lengths
SIEM Query:
source="router_logs" AND (uri="/v2x00.cgi" OR message="crash" OR message="reboot")