CVE-2025-9935
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on TOTOLINK N600R routers via command injection in the web interface. Attackers can take full control of affected devices without authentication. All users running the vulnerable firmware version are affected.
💻 Affected Systems
- TOTOLINK N600R
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent malware, pivot to internal networks, intercept traffic, or use the device in botnets.
Likely Case
Device takeover for credential theft, network reconnaissance, or participation in DDoS attacks.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Public exploit code exists on GitHub. Attack requires sending crafted HTTP requests to the vulnerable endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.totolink.net/
Restart Required: Yes
Instructions:
1. Check vendor website for firmware updates. 2. Download latest firmware. 3. Log into router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable WAN access to web interface
allPrevent external access to the vulnerable web management interface
Login to router admin → Security/Firewall → Disable remote management/remote access
Network segmentation
allIsolate router management interface to trusted network segments only
🧯 If You Can't Patch
- Replace affected devices with supported models from different vendors
- Implement strict network access controls to limit exposure of management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under System Status or Firmware Upgrade sectionCheck Version:
curl -s http://router-ip/cgi-bin/cstecgi.cgi | grep version or check web interfaceVerify Fix Applied:
Verify firmware version is newer than 4.3.0cu.7866_B20220506📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to /cgi-bin/cstecgi.cgi with shell metacharacters
- Unexpected command execution in system logs
Network Indicators:
- HTTP requests containing shell commands (;, |, &, $, etc.) to router management port
- Outbound connections from router to suspicious IPs
SIEM Query:
source="router_logs" AND uri="/cgi-bin/cstecgi.cgi" AND (command="*;*" OR command="*|*" OR command="*&*" OR command="*$(*")