CVE-2025-4809
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Tenda AC7 routers allows remote attackers to execute arbitrary code by manipulating the deviceList parameter in the fromSafeSetMacFilter function. 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, creation of persistent backdoors, lateral movement to internal networks, 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, though internal attacks remain possible.
🎯 Exploit Status
Exploit details have been publicly disclosed, making weaponization highly probable. The vulnerability requires no authentication and has straightforward exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.tenda.com.cn/
Restart Required: Yes
Instructions:
1. Check Tenda's official website for security advisories. 2. If a patch is released, download the firmware update. 3. Access router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply the new firmware. 6. Reboot the router.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to the vulnerable web interface
Access router admin interface -> System Tools -> Remote Management -> Disable
Network Segmentation
allIsolate Tenda AC7 routers from critical networks
🧯 If You Can't Patch
- Place affected routers behind firewalls with strict inbound filtering to block external access to management interfaces
- Implement network monitoring for unusual traffic patterns or exploitation attempts targeting the /goform/setMacFilterCfg endpoint
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via admin interface: System Tools -> Firmware Upgrade. If version is 15.03.06.44, device is vulnerable.Check Version:
curl -s http://router-ip/goform/getStatus | grep version (if API available) or check web interface manuallyVerify Fix Applied:
After applying any vendor patch, verify firmware version is no longer 15.03.06.44 and test that the /goform/setMacFilterCfg endpoint properly validates input length.📡 Detection & Monitoring
Log Indicators:
- Unusually long deviceList parameter values in web logs
- Multiple failed exploitation attempts to /goform/setMacFilterCfg
- Unexpected process crashes or reboots
Network Indicators:
- HTTP POST requests to /goform/setMacFilterCfg with oversized deviceList parameters
- Unusual outbound connections from router to unknown IPs
SIEM Query:
source="router_logs" AND uri="/goform/setMacFilterCfg" AND (deviceList.length>100 OR status=500)