CVE-2025-5903
📋 TL;DR
A critical buffer overflow vulnerability in TOTOLINK T10 routers allows remote attackers to execute arbitrary code by sending specially crafted POST requests to the /cgi-bin/cstecgi.cgi endpoint. This affects the setWiFiAclRules function when manipulating the 'desc' argument. Anyone using TOTOLINK T10 routers with the vulnerable firmware is at risk.
💻 Affected Systems
- TOTOLINK T10
📦 What is this software?
T10 Firmware by Totolink
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network infiltration, data theft, and persistent backdoor installation.
Likely Case
Router takeover enabling traffic interception, DNS manipulation, credential harvesting, and lateral movement into connected networks.
If Mitigated
Denial of service or limited impact if network segmentation and strict access controls prevent exploitation.
🎯 Exploit Status
Exploit details have been publicly disclosed, making weaponization straightforward. No authentication is required for exploitation.
🛠️ 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
Disable Remote Management
allPrevent external access to the router's web interface
Access router admin interface -> Advanced Settings -> Remote Management -> Disable
Network Segmentation
allIsolate TOTOLINK T10 routers from critical networks
Configure firewall rules to restrict access to router management interface
🧯 If You Can't Patch
- Immediately isolate affected routers from internet and critical internal networks
- Implement strict network access controls and monitor for exploitation attempts
🔍 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 -i versionVerify Fix Applied:
Verify firmware version has been updated to a version later than 4.1.8cu.5207📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cgi-bin/cstecgi.cgi with large desc parameters
- Multiple failed buffer overflow attempts in system logs
Network Indicators:
- HTTP POST requests to router IP on port 80/443 targeting /cgi-bin/cstecgi.cgi with abnormal payload sizes
SIEM Query:
source="router_logs" AND (uri="/cgi-bin/cstecgi.cgi" AND method="POST" AND size>1024)🔗 References
- https://candle-throne-f75.notion.site/TOTOLINK-T10-setWiFiAclRules-20bdf0aa118580399a8df6ba2a44c197
- https://vuldb.com/?ctiid.311676
- https://vuldb.com/?id.311676
- https://vuldb.com/?submit.592247
- https://www.totolink.net/
- https://candle-throne-f75.notion.site/TOTOLINK-T10-setWiFiAclRules-20bdf0aa118580399a8df6ba2a44c197
