CVE-2025-5853
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Tenda AC6 routers allows remote attackers to execute arbitrary code by manipulating the remoteIp parameter. This affects Tenda AC6 routers running firmware version 15.03.05.16. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Tenda AC6
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, lateral movement to internal networks, persistent backdoor installation, and data exfiltration.
Likely Case
Router takeover enabling traffic interception, DNS manipulation, credential theft, and use as botnet node.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access and proper network segmentation.
🎯 Exploit Status
Exploit details have been publicly disclosed. The vulnerability is in a web form handler, making exploitation straightforward for attackers with basic skills.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.tenda.com.cn/
Restart Required: Yes
Instructions:
1. Check Tenda website for firmware updates. 2. Download latest firmware for AC6 model. 3. Log into router admin interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload and install new firmware. 6. Reboot router after installation.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to router web interface
Log into router admin > System Tools > Remote Management > Disable
Restrict WAN Access
linuxBlock external access to router management ports
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Isolate affected routers in separate VLAN with strict firewall rules
- Implement network monitoring for exploitation attempts and anomalous traffic
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System Status or System Tools > Firmware UpgradeCheck Version:
curl -s http://router-ip/goform/GetSysInfo | grep firmwareVerify Fix Applied:
Verify firmware version is no longer 15.03.05.16 and test remote management interface functionality📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/SetRemoteWebCfg
- Multiple failed buffer overflow attempts in system logs
- Abnormal process creation or crashes
Network Indicators:
- Traffic to router management port with malformed remoteIp parameter
- Unexpected outbound connections from router
- DNS queries to suspicious domains
SIEM Query:
source="router.log" AND (url="/goform/SetRemoteWebCfg" OR "formSetSafeWanWebMan") AND remoteIp="*"