CVE-2025-7421
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Tenda O3V2 routers allows remote attackers to execute arbitrary code by manipulating the 'mac' parameter in the MAC filter modification function. This affects devices running firmware version 1.0.0.12(3880) with the vulnerable httpd component exposed. Attackers can exploit this remotely without authentication to potentially take full control of affected routers.
💻 Affected Systems
- Tenda O3V2
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, persistent backdoor installation, network traffic interception, and lateral movement to connected devices.
Likely Case
Router takeover enabling DNS hijacking, credential theft from network traffic, and botnet recruitment for DDoS attacks.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access, though internal network attacks remain possible.
🎯 Exploit Status
Public proof-of-concept exploit code is available in GitHub repositories. The vulnerability requires no authentication and has straightforward exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Tenda's official website for firmware updates. 2. If update available, download and install via router admin interface. 3. Reboot router after installation. 4. Verify firmware version is no longer 1.0.0.12(3880).
🔧 Temporary Workarounds
Disable WAN access to admin interface
allPrevent remote exploitation by blocking external access to router management interface
Access router admin panel > Security > Remote Management > Disable
Network segmentation
allIsolate router management interface to separate VLAN
🧯 If You Can't Patch
- Replace affected router with different model/vendor
- Place router behind dedicated firewall with strict ingress filtering
🔍 How to Verify
Check if Vulnerable:
Access router admin interface and check firmware version under System Status or About page. If version is exactly 1.0.0.12(3880), device is vulnerable.Check Version:
curl -s http://router-ip/goform/getStatus | grep versionVerify Fix Applied:
After firmware update, verify version has changed from 1.0.0.12(3880). Test MAC filter modification functionality to ensure no crashes occur.📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /goform/operateMacFilter with unusually long 'mac' parameter
- Router crash/restart logs
- Unusual process execution in system logs
Network Indicators:
- Multiple failed exploitation attempts to router management interface
- Unusual outbound connections from router
SIEM Query:
source="router_logs" AND (uri="/goform/operateMacFilter" AND content_length>100) OR (event="crash" AND process="httpd")🔗 References
- https://github.com/wudipjq/my_vuln/blob/main/Tenda3/vuln_54/54.md
- https://github.com/wudipjq/my_vuln/blob/main/Tenda3/vuln_54/54.md#poc
- https://vuldb.com/?ctiid.315881
- https://vuldb.com/?id.315881
- https://vuldb.com/?submit.608867
- https://www.tenda.com.cn/
- https://github.com/wudipjq/my_vuln/blob/main/Tenda3/vuln_54/54.md
