A stack‑based buffer overflow occurs in the formSetPPTPServer function of the Tenda CX12L firmware. By sending a crafted request to the /goform/SetPptpServerCfg endpoint, an attacker can overwrite return addresses on the stack, enabling execution of arbitrary code. The vulnerability allows an adversary to compromise the router’s control plane, granting full control over the device and any networks connected through it.

Tenda CX12L routers running firmware version 16.03.53.12 are affected. The flaw resides in the PPTP server configuration interface exposed to the WAN. No other vendors or products are listed by the CNA as impacted.

The CVSS score of 8.7 places the flaw in the High severity range. Although the EPSS score is not available, the exploit is publicly known and can be carried out remotely without authentication. The vulnerability is not listed in the CISA KEV catalog, but the lack of mitigation guidance and the remote nature of the attack result in a significant risk to affected deployments.