CVE-2025-11091
📋 TL;DR
A buffer overflow vulnerability exists in Tenda AC21 routers through firmware version 16.03.08.16. Attackers can remotely exploit this flaw by sending specially crafted requests to the /goform/SetStaticRouteCfg endpoint, potentially allowing arbitrary code execution. This affects all users running vulnerable firmware versions.
💻 Affected Systems
- Tenda AC21
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote attackers could execute arbitrary code with router privileges, potentially taking full control of the device, intercepting network traffic, or using it as a foothold for further attacks.
Likely Case
Remote code execution leading to router compromise, allowing attackers to modify configurations, intercept traffic, or launch attacks against internal networks.
If Mitigated
If properly segmented and firewalled, impact could be limited to the router itself without lateral movement to other systems.
🎯 Exploit Status
Public exploit code is available, making exploitation straightforward for attackers with basic skills.
🛠️ 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 administration
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 different models or brands
- Implement strict network access controls to limit exposure to router management interfaces
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is 16.03.08.16 or earlier, the device is vulnerable.Check Version:
Check via router web interface at 192.168.0.1 or 192.168.1.1, or via SSH if enabled: cat /proc/versionVerify Fix Applied:
Verify firmware version has been updated to a version later than 16.03.08.16.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/SetStaticRouteCfg
- Multiple failed login attempts followed by buffer overflow patterns
Network Indicators:
- Unusual traffic patterns to router management ports
- Exploit payloads in HTTP requests to router
SIEM Query:
source="router_logs" AND (uri="/goform/SetStaticRouteCfg" OR message="buffer overflow")