CVE-2026-1637
π TL;DR
This CVE describes a stack-based buffer overflow vulnerability in Tenda AC21 routers running firmware version 16.03.08.16. Attackers can remotely exploit this vulnerability to execute arbitrary code or crash the device. Users of affected Tenda AC21 routers with the vulnerable firmware are at risk.
π» Affected Systems
- Tenda AC21
β οΈ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network infiltration, and persistent backdoor installation.
Likely Case
Router crash causing denial of service, potential credential theft, and network disruption.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access and proper network segmentation.
π― Exploit Status
Public exploit available on GitHub, making exploitation straightforward for attackers with basic skills.
π οΈ Fix & Mitigation
β 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. Log into router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
π§ Temporary Workarounds
Disable WAN Management
allPrevent remote access to router administration interface from WAN side
Network Segmentation
allIsolate router management interface to separate VLAN or network segment
π§― If You Can't Patch
- Replace affected router with different model or vendor
- Place router behind firewall with strict inbound rules blocking all unnecessary ports
π How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is exactly 16.03.08.16, device is vulnerable.Check Version:
Login to router admin interface and check System Status or Firmware Information pageVerify Fix Applied:
After firmware update, verify version has changed from 16.03.08.16 to a newer version.π‘ Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/AdvSetMacMtuWan
- Router crash/reboot logs
- Memory corruption errors in system logs
Network Indicators:
- Unusual traffic patterns to router management interface
- Exploit payload patterns in network traffic
SIEM Query:
source="router_logs" AND (uri="/goform/AdvSetMacMtuWan" OR message="buffer overflow" OR message="segmentation fault")