CVE-2025-11524
📋 TL;DR
A stack-based buffer overflow vulnerability in Tenda AC7 routers allows remote attackers to execute arbitrary code by manipulating the ddnsEn parameter in the SetDDNSCfg endpoint. This affects Tenda AC7 routers running firmware version 15.03.06.44. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Tenda AC7
📦 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 botnet recruitment.
Likely Case
Device takeover for credential theft, DNS hijacking, or use as proxy for attacks on internal networks.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access, though internal threats remain.
🎯 Exploit Status
Public exploit code available on GitHub. Attack requires sending crafted HTTP POST request to /goform/SetDDNSCfg endpoint.
🛠️ 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 AC7 model. 3. Access router admin interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable WAN Management Access
allPrevent external access to router management interface
Access router admin > Advanced > System Tools > Remote Management > Disable
Block SetDDNSCfg Endpoint
linuxUse firewall rules to block access to vulnerable endpoint
iptables -A INPUT -p tcp --dport 80 -m string --string "/goform/SetDDNSCfg" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --string "/goform/SetDDNSCfg" --algo bm -j DROP
🧯 If You Can't Patch
- Isolate affected routers in separate network segment with strict firewall rules
- Implement network-based intrusion detection to monitor for exploit attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under System Status or System Tools. If version is 15.03.06.44, device is vulnerable.Check Version:
curl -s http://router-ip/goform/GetSysInfo | grep -i version || Check web interface manuallyVerify Fix Applied:
Verify firmware version has changed from 15.03.06.44 to a newer version. Test if /goform/SetDDNSCfg endpoint still accepts malformed ddnsEn parameter.📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /goform/SetDDNSCfg with abnormal ddnsEn parameter length
- Router crash/reboot logs following web interface access
Network Indicators:
- Unusual outbound connections from router after exploit
- HTTP requests with overly long parameters to router management port
SIEM Query:
source="router_logs" AND uri_path="/goform/SetDDNSCfg" AND (param_length>100 OR status_code=500)