Executive brief
The Tenda W3 wireless router, used for home and small office networking, contains a security flaw in its web management interface. By sending a specially crafted web request, an attacker can crash the router, causing it to reboot or become unresponsive. This results in a loss of internet connectivity for all connected users and may require a manual restart to restore service.
Technical details
A stack-based buffer overflow exists in the 'formSetCfm' CGI handler of the Tenda W3 router. The vulnerability is located within the 'save_list_data' function, which is called when the 'funcname' parameter is set to 'save_list_data'. The root cause is an unsafe 'sprintf' call (sprintf(acStack_154, "%s.listnum", param_1)) that processes the user-controlled 'funcpara1' parameter without length validation. An unauthenticated remote attacker can exploit this by sending a crafted HTTP request to the 'setcfm' endpoint, leading to a crash of the web service or the entire device (Denial of Service). While primarily a DoS risk, stack overflows of this nature may potentially allow for arbitrary code execution.
Affected products
- Tenda (Shenzhen Tenda Technology Co., Ltd) W3 Wireless Router v1.0.0.3(2204)
Timeline
- 2026-03-10: other: CVE request submitted to MITRE
- 2026-06-06: disclosed: Public disclosure via GitHub repository
- 2026-06-09: advisory: NVD published date