CVE-2025-4897
📋 TL;DR
This critical vulnerability in Tenda A15 routers allows remote attackers to execute arbitrary code via a buffer overflow in the HTTP POST request handler. Attackers can exploit this without authentication to potentially take full control of affected devices. All users running vulnerable firmware versions are at risk.
💻 Affected Systems
- Tenda A15
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network traffic interception, lateral movement to other devices, and botnet recruitment.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept traffic, or use the device as a pivot point for further attacks.
If Mitigated
Limited impact if device is behind firewall with strict inbound rules, though internal network exposure remains possible.
🎯 Exploit Status
Public exploit code available on GitHub. Attack requires sending specially crafted HTTP POST request to /goform/multimodalAdd 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. 3. Access router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Block External Access
linuxPrevent external exploitation by blocking inbound access to router web interface
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Disable Remote Management
allTurn off remote administration feature in router settings
🧯 If You Can't Patch
- Isolate vulnerable routers in separate network segment with strict firewall rules
- Implement network monitoring for suspicious POST requests to /goform/multimodalAdd
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is 15.13.07.09 or 15.13.07.13, device is vulnerable.Check Version:
curl -s http://router-ip/ | grep -i firmware || Check web interface System Status pageVerify Fix Applied:
After firmware update, verify version has changed from vulnerable versions. Test with controlled exploit attempt if possible.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/multimodalAdd
- Large payloads in POST requests
- Multiple failed login attempts followed by POST to vulnerable endpoint
Network Indicators:
- HTTP POST requests to /goform/multimodalAdd with abnormal payload sizes
- Traffic from unexpected sources to router management port
SIEM Query:
source="router_logs" AND uri="/goform/multimodalAdd" AND method="POST" AND (bytes_out>1000 OR status_code=500)