CVE-2025-45789
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on TOTOLINK A3100R routers via a buffer overflow in the setParentalRules function. Attackers can exploit this by sending specially crafted requests containing overly long urlKeyword parameters. All users running the vulnerable firmware version are affected.
💻 Affected Systems
- TOTOLINK A3100R
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent remote access, network traffic interception, lateral movement to other devices, and potential botnet recruitment.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept traffic, or use the device as a pivot point for further attacks.
If Mitigated
Limited impact if device is behind firewall with strict inbound filtering and not exposed to untrusted networks.
🎯 Exploit Status
Public GitHub repository contains proof-of-concept code. Exploitation requires network access to the router's web interface.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown
Restart Required: Yes
Instructions:
1. Check TOTOLINK official website for firmware updates. 2. Download latest firmware. 3. Log into router admin panel. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Network Segmentation
allIsolate router management interface from untrusted networks
Access Control
linuxRestrict access to router web interface using firewall rules
iptables -A INPUT -p tcp --dport 80 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
🧯 If You Can't Patch
- Replace vulnerable device with supported hardware
- Implement strict network segmentation and monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in web interface under System Status > Firmware VersionCheck Version:
curl -s http://router-ip/status.cgi | grep firmwareVerify Fix Applied:
Verify firmware version is newer than V5.9c.1527📡 Detection & Monitoring
Log Indicators:
- Unusually long HTTP POST requests to /cgi-bin/cstecgi.cgi
- Multiple failed buffer overflow attempts in system logs
- Unexpected process crashes or restarts
Network Indicators:
- HTTP requests with abnormally long urlKeyword parameters
- Traffic to router management interface from unexpected sources
- POST requests to setParentalRules endpoint
SIEM Query:
source="router_logs" AND (urlKeyword.length>100 OR "setParentalRules" AND POST)