A stack-based buffer overflow occurs when the time_zone argument is processed by the sub_40785C function in /cgi-bin/adm.cgi on Wavlink WL‑NU516U1. Manipulating this input can corrupt the stack, allowing an attacker to execute arbitrary code with the privileges of the web server process. The exploit requires remote access to the administrative CGI interface and is considered to have high complexity, though publicly available proof‑of‑concept code demonstrates that it can ultimately lead to full compromise of the device.

The vulnerability affects the Wavlink WL‑NU516U1 router model running firmware version 20251208. No other firmware revisions are listed as vulnerable at this time.

The CVSS score is 7.5, indicating high severity. The EPSS score is less than 1%, suggesting a low probability of mass exploitation, but the existence of a publicly available exploit and the vendor's lack of response means that local threats are still real. The vulnerability is not included in the CISA KEV catalog. Attackers can exploit it remotely by sending crafted time_zone values to /cgi-bin/adm.cgi; due to the buffer overflow they can potentially achieve remote code execution.