CVE-2025-67186
📋 TL;DR
This critical buffer overflow vulnerability in TOTOLINK A950RG routers allows remote attackers to execute arbitrary code or cause denial of service by sending specially crafted requests to the setUrlFilterRules interface. Attackers can exploit this without authentication to potentially take full control of affected devices. All users running the vulnerable firmware version are affected.
💻 Affected Systems
- TOTOLINK A950RG
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains full root shell access to the router, enabling persistent backdoor installation, network traffic interception, lateral movement to internal networks, and complete device compromise.
Likely Case
Remote attacker crashes the router causing denial of service, or executes limited code to modify configurations, intercept traffic, or use the device as a botnet node.
If Mitigated
Attack attempts are detected and blocked at network perimeter, with no successful exploitation due to proper segmentation and monitoring.
🎯 Exploit Status
Public proof-of-concept exists in GitHub repository. Exploitation requires sending crafted HTTP POST request to vulnerable endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown
Restart Required: No
Instructions:
1. Check TOTOLINK official website for firmware updates
2. If update available, download and verify checksum
3. Access router web interface
4. Navigate to System Tools > Firmware Upgrade
5. Upload new firmware file
6. Wait for automatic reboot
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to router management interface
Network Segmentation
allIsolate router management interface to trusted network only
🧯 If You Can't Patch
- Block access to /lib/cste_modules/firewall.so endpoint at network perimeter
- Implement strict firewall rules to limit router management interface access to trusted IPs only
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System Status > Firmware VersionCheck Version:
curl -s http://router-ip/cgi-bin/luci/ | grep -i versionVerify Fix Applied:
Verify firmware version has changed from V4.1.2cu.5204_B20210112 to newer version📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /lib/cste_modules/firewall.so
- Large payloads in URL parameter
- Router crash/restart logs
Network Indicators:
- HTTP POST requests with abnormally long URL parameters to router management interface
- Traffic spikes to router on management ports
SIEM Query:
source="router_logs" AND (uri="/lib/cste_modules/firewall.so" OR message="buffer overflow" OR message="segmentation fault")