CVE-2025-5902
📋 TL;DR
This critical vulnerability in TOTOLINK T10 routers allows remote attackers to execute arbitrary code via a buffer overflow in the firmware upgrade function. Attackers can exploit this by sending specially crafted POST requests to the vulnerable CGI endpoint. All users running the affected firmware version are at risk.
💻 Affected Systems
- TOTOLINK T10
📦 What is this software?
T10 Firmware by Totolink
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network traffic interception, and lateral movement to other devices on the network.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept traffic, or use the device as part of a botnet.
If Mitigated
Limited impact if the device is behind strict network segmentation with no internet-facing access.
🎯 Exploit Status
Public exploit details are available, and the vulnerability requires no authentication, making exploitation straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.totolink.net/
Restart Required: Yes
Instructions:
1. Check TOTOLINK website for firmware updates. 2. Download latest firmware. 3. Access router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Network Segmentation
allIsolate TOTOLINK T10 routers from untrusted networks and restrict access to management interface.
Access Control Lists
linuxImplement firewall rules to block external access to port 80/443 on affected devices.
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Replace affected devices with supported models from different vendors
- Implement strict network monitoring and anomaly detection for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface or via SSH: cat /proc/version | grep -i totolinkCheck Version:
curl -s http://router-ip/cgi-bin/cstecgi.cgi | grep -i version || ssh admin@router-ip 'cat /proc/version'Verify Fix Applied:
Verify firmware version has been updated to a version newer than 4.1.8cu.5207📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cgi-bin/cstecgi.cgi with large slaveIpList parameters
- Multiple failed firmware upgrade attempts
Network Indicators:
- HTTP POST requests to /cgi-bin/cstecgi.cgi with abnormal payload sizes
- Traffic patterns suggesting buffer overflow exploitation
SIEM Query:
source="router_logs" AND uri="/cgi-bin/cstecgi.cgi" AND method="POST" AND (bytes_sent>10000 OR contains(body, "slaveIpList"))🔗 References
- https://candle-throne-f75.notion.site/TOTOLINK-T10-setUpgradeFW-20bdf0aa11858089bc28f634bb140d00
- https://vuldb.com/?ctiid.311675
- https://vuldb.com/?id.311675
- https://vuldb.com/?submit.592246
- https://www.totolink.net/
- https://candle-throne-f75.notion.site/TOTOLINK-T10-setUpgradeFW-20bdf0aa11858089bc28f634bb140d00
