CVE-2025-7913
📋 TL;DR
This critical vulnerability in TOTOLINK T6 routers allows remote attackers to execute arbitrary code via a buffer overflow in the MQTT service's updateWifiInfo function. Attackers can exploit this by sending specially crafted serverIp parameter values to gain control of affected devices. All users running vulnerable firmware versions are at risk.
💻 Affected Systems
- TOTOLINK T6
📦 What is this software?
T6 Firmware by Totolink
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network traffic interception, lateral movement to other devices, and botnet recruitment.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept network traffic, or use the device as a pivot point for further attacks.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering or if MQTT service is disabled.
🎯 Exploit Status
Public proof-of-concept code exists, making exploitation straightforward for attackers with basic skills.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: Yes
Instructions:
1. Check TOTOLINK official website for firmware updates
2. If update available, download and follow vendor flashing instructions
3. Factory reset after update to ensure clean configuration
🔧 Temporary Workarounds
Disable MQTT Service
allTurn off the vulnerable MQTT service component if not required
Network Segmentation
allIsolate affected routers in separate VLANs with strict firewall rules
🧯 If You Can't Patch
- Block inbound access to router management interfaces (typically ports 80, 443, 1883) from untrusted networks
- Implement strict egress filtering to prevent compromised devices from communicating with attacker C2 servers
🔍 How to Verify
Check if Vulnerable:
Check router web interface or CLI for firmware version matching affected versionCheck Version:
Check router web interface at http://[router-ip]/ or use telnet/ssh if enabledVerify Fix Applied:
Verify firmware version has been updated to a version newer than 4.1.5cu.748_B20211015📡 Detection & Monitoring
Log Indicators:
- Unusual MQTT connection attempts
- Buffer overflow error messages in system logs
- Unexpected configuration changes
Network Indicators:
- Traffic to router on MQTT port 1883 from external sources
- Suspicious payloads containing long serverIp parameters
SIEM Query:
source="router-logs" AND ("buffer overflow" OR "updateWifiInfo" OR "serverIp" AND length>100)