An unauthenticated attacker can exploit a stack‑based buffer overflow in the firewall.cgi and makeRequest.cgi binaries of the WDR201A WiFi Extender. By sending a POST request whose Content‑Length header exceeds 512 bytes, the attacker bypasses length checks in a fgets() call and overwrites the saved return address, enabling arbitrary code execution via return‑oriented programming or return‑to‑libc techniques.

Shenzhen Yipu Commercial and Trading Co., Ltd supplies the WDR201A WiFi Extender (hardware V2.1, firmware LFMZX28040922V1.02). These devices are affected by the vulnerability.

The CVSS score of 8.3 indicates high severity. No EPSS score is available, and the vulnerability is not listed in the CISA KEV catalog. Because authentication is not required and the flaw resides in a web‑accessible CGI script, an attacker can trigger the overflow directly from the internet or an adjacent network, making exploitation relatively straightforward.