CVE-2026-2874
📋 TL;DR
A stack-based buffer overflow vulnerability in Tenda A21 routers allows remote attackers to execute arbitrary code by manipulating the SSID parameter. This affects Tenda A21 routers running firmware version 1.0.0.0. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Tenda A21
📦 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 compromise allowing traffic interception, DNS hijacking, credential theft, and use as botnet node for DDoS attacks.
If Mitigated
Limited impact with proper network segmentation, but still vulnerable to denial of service if exploited.
🎯 Exploit Status
Public exploit code exists in GitHub repository, making exploitation straightforward for attackers.
🛠️ 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. 3. Access router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to router administration interface
Network Segmentation
allIsolate router management interface to separate VLAN
🧯 If You Can't Patch
- Replace affected routers with patched or different models
- Implement strict firewall rules blocking all external access to router management interface
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is 1.0.0.0, device is vulnerable.Check Version:
Check via router web interface at 192.168.0.1 or 192.168.1.1Verify Fix Applied:
Verify firmware version has been updated to a version later than 1.0.0.0📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/fast_setting_wifi_set with long SSID parameters
- Router crash/reboot logs
- Unusual outbound connections from router
Network Indicators:
- Exploit traffic patterns to router management interface
- Unusual DNS queries from router
- Router responding abnormally to management requests
SIEM Query:
source="router_logs" AND (uri="/goform/fast_setting_wifi_set" AND content_length>100) OR (event="crash" AND device="Tenda_A21")